This document provides an introduction to the concept of free cooling using a ground coupled heat exchanger combined with a radiant heating and cooling system. It discusses factors that influence cooling loads in residential buildings such as solar gains, shading, and room variation. The document also examines duration of cooling loads, required cooling capacity, and guidelines for optimal temperature conditions.

1. 02 | 2013
Free cooling guide
COOLI N G I N TEGRATI ON I N LOW-
ENERGY HOU SES

2. Table of contents
1. Introduction to the concept of free cooling ...3
The need for cooling in low-energy houses.............4
Comfort and energy efficiency – the best fit
for low-energy houses ............................................4
Investing for the future – the design of a
low-energy house ...................................................5
2. Cooling loads in residential buildings .............6
Factors influencing the sensible cooling load..........6
Factors influencing the latent cooling load .............7
The effect of shading..............................................7
Room variation .......................................................8
Duration of the cooling load ..................................8
Required cooling capacity.......................................9
3. The ISO 7730 guidelines.................................10
Optimal temperature conditions............................10
Draught rate .........................................................11
Radiant asymmetry ...............................................11
Surface temperatures............................................12
Vertical air temperature difference........................12
4. Capacity and limitations of radiant
emitter systems ..............................................13
Heat flux density...................................................13
Thermal transfer coefficient..................................13
Dew point limitations............................................13
Theoretical capacities of embedded
radiant cooling......................................................14
5. Ground heat exchangers.................................15
Ground conditions ................................................15
Ground heat exchangers .......................................16
Ground temperature profile...................................17
Primary supply temperatures.................................17
Dimensioning of ground heat exchangers
for free cooling .....................................................17
6. Free cooling in combination with
different heat sources ....................................19
7. Choosing and dimensioning the radiant
emitter system................................................20
Capacity of different radiant emitter systems........20
Radiant floor constructions and capacity ..............22
Radiant ceiling constructions and capacity ...........24
Capacity diagrams.................................................24
Regulation and control..........................................26
The self-regulating effect in underfloor heating ..27
Functional description of Uponor Control
System .................................................................27
Component overview ............................................29
8. Uponor Pump and exchanger group (EPG6)
for ground sourced free cooling.....................29
Dimensions ...........................................................30
Pump diagram.......................................................30
Control principle ...................................................31
Installation examples.............................................33
Operation of Uponor Climate Controller C-46.......36
Operation mode of Uponor Climate
Controller C-46 .....................................................36
Dew point management parameters and
settings.................................................................37
Heating and cooling change-over:
external signal.......................................................38
Heating and cooling change-over:
Uponor Climate Controller C-46............................38
2 UPONOR · FREE COOLING G UIDE

3. 1. Introduction to the concept of free cooling
Free cooling is a term generally used when low external
temperatures are used for cooling purposes in buildings.
This guide presents a free cooling concept based on
a ground coupled heat exchanger combined with a
radiant heating and cooling system. A ground coupled
heat exchanger can for example be horizontal collectors,
vertical boreholes or energy cages. A radiant system
means that the floors, ceilings or walls have embedded
pipes in which water is circulated for heating and
cooling of the building. Under floor heating and cooling
is the most well know example of a radiant system.
A radiant system combined with a ground coupled heat
exchanger is highly energy efficient and has several
advantages. In the summer period, the ground coupled
heat exchanger provides cooling temperatures that are
lower compared to the outside air. The radiant system
operates with large surfaces, which means it can utilize
the temperatures from the ground directly for cooling
purposes. The result is that free cooling can be provided
with only cost being the electricity required for running
the circulation pumps in the brine and water systems.
No heat pump is required.
In the heating season the system is operated using a
heat pump. As the ground temperature during winter
is higher compared to the outside air temperature,
the result is improved heat pump efficiency (COP)
compared to an air based heat pump. In addition, the
radiant emitter a system (under floor heating) operates
at moderate water temperatures in large surfaces which
further improves the heat pump COP.
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4. The need for cooling in low-
energy houses
Today, there is a high focus on saving energy and
utilising renewable energy sources in buildings.
The energy demand for space heating is reduced by
increased insulation and tightness of buildings.
However, increased insulation and tightness also
increase the cooling demand. The building becomes
more sensitive to solar radiation through windows and
becomes less able to remove heat in the summer. More
extreme weather conditions further contributes to the
cooling needs and together with an even more increased
consumer awareness of having the right indoor climate,
the need for cooling also in residential buildings will
become a requirement. Optimal architectural design
and shading will help to reduce the cooling need, but
simulations and practical experience show that such
measures alone will not eliminate the cooling need.
Space cooling is needed, not only in the summer, but
also in prolonged periods during spring and autumn
when the low angel of the sun gives high solar radiation
through windows. In order to meet the energy frame
requirements of the building regulations, space cooling
can be provided by utilising renewable energy sources
such as ground heat exchangers for cooling purposes in
conjunction with a radiant system with embedded pipes
in the floor, wall or ceiling.
Cooling needs will differ between rooms and are highly
influenced by direct solar radiation. Rooms with larger
window areas and facing the south will generally have
higher cooling requirements. In periods with high
cooling loads, active cooling is normally required during
both day and night time.
Comfort and energy efficiency
– the best fit for low-energy
houses
Using shading will help to reduce the cooling demand.
However, this forces occupants to actively pull down the
shades e.g. when leaving the house. Also, shading will
block daylight which increases electricity consumption
on artificial light, and shading will block the view which
may not be in the interest of the home occupant.
In fact many architects state that energy efficiency
and comfort may conflict when defining comfort in a
broader sense, such as the freedom to design window
sizes, spaciousness with increased ceiling height,
daylight requirements and the occupant’s tendency to
utilise open doors and windows. All such requirements
put increased demands on the HVAC applications.
Ground heat exchangers combined with radiant systems
is the only “all-in-one” solution, with the ability to
provide both heating and cooling. Such systems are
more cost efficient and simpler to install than having
to deal with a separate heating and cooling systems.
Furthermore, radiant systems are able to heat at a
low supply temperature and cool at a high supply
temperature. This fits perfectly to the typical operating
temperatures of a ground coupled heat exchanger.
Furthermore, the connected heat pump will be able
to run more efficiently and thereby consume less
electricity. In addition, a radiant system provides no
draught problems and provides an optimal temperature
distribution inside a room. Last but not least, radiant
systems provide complete freedom in terms of interior
design, as no physical space is occupied inside the room.
Even more important when looking at the lifetime and
property value of a house, such systems have very low
maintenance need and a lifetime that almost follows
the lifetime of the building itself. In today’s uncertain
environment of future energy prices, free cooling and
ground coupled heat pumps provides a high stability
on the future energy costs of the building in question.
It will most certainly meet today’s and future building
regulations even in a scenario where future property
taxation would be linked to energy efficiency. Hence, it
is an investment that helps to maintain and differentiate
the future property value.
4 UPONOR · FREE COOLING G UIDE

5. Investing for the future – the
design of a low-energy house
A radiant system, e.g. underfloor heating and cooling,
coupled to a ground source heat pump, provides
optimal comfort with high energy efficiency both
summer and winter. In addition, due to the increased
tightness requirements in low-energy houses, a
ventilation system is necessary to maintain an
acceptable indoor air quality. In order to keep the
ventilation system energy efficient, it should be coupled
to a heat recovery ventilation (HRV) unit to minimise
heat losses through the air exchange.
Energy sources for cooling
There are several alternative HVAC applications available
for cooling purposes. A district heating connection is an
energy efficient option for space heating, but cannot
be used for cooling purposes. Alternative means of
cooling could be an air-to-water heat pump, but no
“free cooling” can be extracted from such a system,
hence cooling can only be provided with the heat
pump running causing a higher electricity consumption.
Purely air-based systems like split units can also act as
a cooling system but as can be seen from the picture
below, the efficiency is considerably lower than for
water-based cooling systems.
European seasonal energy efficiency ratio (ESEER) for different cooling
systems. ESEER is defined by the Eurovent Certification Company and
calculated by combining full and part load operating conditions.
Correlation between average property m2
prices and energy class
The figure above shows the correlation between
property prices and the energy efficiency level of the
property in Denmark. Properties with energy class A or
B are on average 6% more expensive than energy class
C and 17% more expensive than energy class D.
DKK/m2
Energy class
0
5
10
15
20
25
Air to air
heat pump
Air to water
heat pump
Brine to water
heat pump
Free
cooling
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6. 2. Cooling loads in residential buildings
The design cooling load (or heat gain) is the amount
of energy to be removed from a house by the
HVAC equipment, to maintain the house at indoor
design temperature when worst case outdoor design
temperature is being experienced. As can be seen
from the figure above, heat gains can come from
external sources, e.g. solar radiation and infiltration
and from internal sources, e.g. occupants and electrical
equipment.
Two important factors when calculating the cooling load
of a house are:
• sensible cooling load
• latent cooling load
The sensible cooling load refers to the air temperature
of the building, and the latent cooling load refers to the
humidity in the building.
Factors influencing the sensible
cooling load
• Windows or doors
• Direct and indirect sunshine through windows,
skylights or glass doors heating up the room
• Exterior walls
• Partitions (that separate spaces of different
temperatures)
• Ceilings under an attic
• Roofs
• Floors over an open crawl space
• Air infiltration through cracks in the building, doors,
and windows
• People in the building
• Equipment and appliances operated in the summer
• Lights
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7. The effect of shading
To reduce the cooling load from solar gains, the most
efficient and sustainable way is to use passive measures.
From an architectural point of view, shading can be
created by building components and by using blinds.
Depending on the type of blinds used, the solar gain
can typically be reduced with up to 85% with external
shading. The figures below show a building simulation
example conducted on a low-energy single family
house, where using different shading factors have been
applied.
Without shading; cooling loads up to 60 W/m2
.
Shading factor 50%; cooling loads up to 40 W/m2
.
Shading factor 85%; cooling loads up to 25 W/m2
.
As can be seen from the figures above, even with the
most efficient shading factor, the cooling load still
amounts to 25 W/m2
.
ExternalheatgainInternalheatgain
Transmission (Sensible)
Solar Radiation (Sensible)
Air
Ventilation
(Sensible)
(Latent)
(Sensible)
(Latent)
(Sensible)
(Sensible)
(Latent)
Lighting
Equipment
People
CONDITIONED
SPACE
Total
sensible
Total
latent
Cooling
Load
2%
5%
3%
10%
13%
15%
52%
Heat from air flows
Heat from occupants
(incl. latent)
Heat from equipment
Heat from walls and
floors (structure)
Heat from lighting
Heat from daylight
(direct solar)
Heat from windows
(including absorbed solar)
and openings
Factors influencing the latent
cooling load
Moisture is introduced into a room through:
• People
• Equipment and appliances
• Air infiltration through cracks in the building, doors,
and windows
Internal gains in residential buildings are limited to the
people normally occupying the space and household
equipment. In national building regulations, the load
for internal gains in ordinary residential buildings is
often mentioned (3-5 W/m2
). In residential buildings,
the cooling load primarily comes from external heat
gains, and mostly from solar gains through windows
and doors, transmission through wall and roof, and
infiltration through the building envelope/ventilation.
The figure below shows that about 2/3 of the cooling
load comes from the solar radiation.
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8. 37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
Temperature[°C]
Time [h]
No window opening, no HRV by-pass
Open windows, no HRV by-pass
Open windows, with HRV by-pass
UFH, no opening window
Room variation
There is a big variation in the cooling load from room
to room, caused by the architectural design of the
building. Large window areas facing the south and west
are needed for daylight requirements and winter heat
gains, but they also incudes high summer cooling loads.
As a result of large south facing window areas, the
cooling demand in south facing rooms are higher than
in the north facing rooms. In addition, the desired
temperature levels of each room may differ ranging
from the highest temperature requirements in the
bathroom, to the lowest temperature requirements in
the bedroom.
Duration of the cooling load
The figures below show the duration of over-tempera-
ture with different shading and ventilation strategies.
The data originates from a full year building simulation
of a low-energy single family house in Northern
European climatic conditions (Denmark).
Without shading; over-temperature up to 2 300 hours per year.
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
Temperature[°C]
Time [h]
No window opening, no HRV by-pass
Open windows, no HRV by-pass
Open windows, with HRV by-pass
UFH, no opening window
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
7000
7500
8000
8500
Temperature[°C]
Time [h]
No window opening, no HRV by-pass
Open windows, no HRV by-pass
Open windows, with HRV by-pass
UFH, no opening window
Shading factor 50%; over-temperature up to 1 100 hours per year. Shading factor 85%; over-temperature up to 800 hours per year.
The simulations show that without active cooling
there will be a significant amount of time with over-
temperature (assuming that the maximum temperature
allowed is 26 °C). All the cases also show that
with radiant floor cooling, it is possible to keep the
temperature below 26 °C all year round. National
building regulations across Europe have already started
to implement maximum duration periods of over-
temperature. In Denmark, the requirement in the 2015
standard is that a temperature above 26 °C is only
allowed for maximum 100 h during the year and above
27 °C for maximum 25 h during the year.
8 UPONOR · FREE COOLING G UIDE

9. 5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Capacity[W]
January
February
March
April
May
June
July
August
September
October
November
December
Cooling
Heating
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Capacity[W]
January
February
March
April
May
June
July
August
September
October
November
December
Cooling
Heating
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Capacity[W]
January
February
March
April
May
June
July
August
September
October
November
December
Cooling
Heating
Required cooling capacity
Based on the peak load calculations of the building, the
heating and cooling system can be designed. The HVAC
system should be designed to cover the worst case
(peak load). The figures below show an example of the
variation of the needed capacity to cover the heating
and cooling loads.
Required heating and cooling capacity
Low energy building, shading in-between windows.
Window opening and HRV by-pass are used during cooling season
Low energy building, external shading.
Window opening and HRV by-pass are used during cooling season
As can be seen, the cooling capacity peaks are actually
higher (up to 4 kW), than the heating capacity peaks
(up to 3.5 kW) under any shading conditions (excluding
domestic hot water). Although, the heating period
still remain longer than the total cooling period, it is
interesting to note that the cooling period extends into
early spring and late autumn.
Low energy building, no shading.
Window opening and HRV by-pass are used during cooling season
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10. In order to provide thermal comfort, it is necessary
to take into account local thermal discomfort caused
by temperature deviations, draught, vertical air
temperature difference, radiant temperature asymmetry,
and floor surface temperatures. These factors can
influence on the required capacity of the HVAC system.
Optimal temperature conditions
EN ISO 7730 is an international standard that can be
used as a guideline to meet an acceptable indoor and
thermal environment. These are typically measured in
terms of predicted percentage of dissatisfied (PPD)
and predicted mean vote (PMV). PMV/PPD basically
predicts the percentage of a large group of people
that are likely to feel “too warm” or “too cold” (the
EN ISO 7730 is not replacing national standards and
requirements, which always must be followed).
PMV and PPD
The PMV is an index that predicts the mean value of
the votes of a large group pf persons on a seven-point
thermal sensation scale (see table below), based on the
heat balance of the human body. Thermal balance is
obtained when the internal heat production in the body
is equal to the loss of heat to the environment.
PMV Predicted mean vote
PPD Predicted percentage dissatisfied [%]
+3 Hot
+2 Warm
+1 Slightly warm
0 Neutral
-1 Slightly cold
-2 Cool
-3 Cold
Seven-point thermal sensation scale
The PPD predics the number of thermally dissatisfied
persons among a large group of people. The rest of
the group will feel thermally neutral, slightly warm or
slightly cool.
The table below shows the desired operative tempera-
ture range during summer and winter, taking into con-
sideration normal clothing and activity level in order to
achieve different comfort classes.
Class
Comfort requirements Temperature range
PPD
[%]
PMV
[/]
Winter
1.0 clo
1.2 met
[°C]
Summer
0.5 clo
1.2 met
[°C]
A < 6 - 0.2 < PMV < + 0.2 21-23 23.5-25.5
B < 10 - 0.5 < PMV < + 0.5 20-24 23.0-26.0
C < 15 - 0.7 < PMV < + 0.7 19-25 22.0-27.0
ISO 7730 basically recommends a target temperature
of 22 °C in the winter, and 24.5 °C in the summer. The
higher the deviation around these target temperatures,
the higher the percentage of dissatisfied. The reason
for the different target temperatures is because that the
two seasons apply different clothing conditions as can
be seen in below figure:
Operative temperature for winter and summer clothing
Dissatisfied[%]
PPD
PMV
Operative temperature [°C]
Basic clothing
insulation: 0.5
PredictedPercentageof
Dissatisfied[%]
Basic clothing
insulation: 1.0
Metabolic rate:
1.2
3. The ISO 7730 guidelines
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11. 1
80
2
4
6
20
8
0 5 10 20 30 352515
0 9 18 36 54 634527
[°C]
[°F]
60
40
10
Dissatisfied[%]
Radiant temperature asymmetry [°C]
Warm ceiling Cool wall
Cool ceiling Warm wall
Radiant asymmetry
When designing a radiant ceiling or wall system, make
sure to stay within the limits of radiant asymmetry. As
can be seen in the figure below, the radiant asymmetry
differs depending on the location of the emitter system,
and whether it’s used for heating or cooling.
With the insulation levels typically used today, radiant
asymmetry does normally not cause any problems
due to the moderate heating and cooling load the
emitter has to perform. However, especially when using
ceiling heating, a calculation must be made for a given
reference room.
When designing radiant cooling systems, the dew point
is normally reached before radiant asymmetry problems
occur. Can be calculated according to ISO 7726.
0
0.4
0.05
0.2
0.15
0.25
0.35
0.2
0.3
0.5 41 1.5 2 2.5 3 3.5 4.5
3.0 K
4.0 K
5.0 K
6.0 K
7.0 K
8.0 K
9.0 K
10.0 K
Maximumairvelocity,0.5mfromwall[m/s]
Recommended comfort limit for
sedentary persons
Height of cool wall [m]
Δt (wall-room)
Draught rate
Radiant systems are low convective systems and will
not create any problems with draught. However, down
draught from a cold wall can put a limitation to the
system. A cold wall can create draught as we know from
windows. When designing wall cooling, the velocity on
the air need to be within the recommendation (Class A
is 0.18 m/s).
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12. Dissatisfied
Floor temperature
Local discomfort caused by warm and cool floors
Surface temperatures
For many years, people have chosen underfloor heating
systems as the preferred emitter system, because of the
perceived comfort of walking on a warm floor. Similarly,
the question is if the occupants complaint about discom-
fort when utilising the floor to remove heat (cooling).
According to ISO 7730, the lowest PPD (6%) is found
at a floor temperature of 24 °C. A typical floor cooling
system will have to operate with a minimum floor
temperature of 20 °C, where the expected PPD would
still be under 10%. As will be seen later, such floor
temperatures still provide a significant cooling effect,
due to the large surface area being emitted.
Vertical air temperature
difference
The comfort categories are divided into A, B and C
depending upon the difference between the air
temperature at floor level and at a height equivalent to
a seated person. As can be seen below, the temperature
difference must be under 2°C in order to reach
category A.
Category
Vertical air temperature difference a
°C
A < 2
B < 3
C < 4
a) 1,1 and 0,1 m above floor
A study done by Deli in 1995 shows the correlation
between the ΔT floor surface/room (difference between
the floor surface temperature and the dimensioned
room temperature) and the vertical air temperature
difference.
Vertical temperature profile with different emitter systems
[°C]
18 20 22 2624
Ideal heating Underfloor heating
Radiant ceiling heating External wall radiator heating
Temperature profile radiant cooling
[°C]
18 20 22 2624
Radiant floor
cooling
Radiant ceiling
cooling
Radiant wall
cooling
Correlation between the temperature difference floor surface to room
and the vertical air temperature difference (Deli, 1995).
The study concludes that up to a ΔT 8K, the comfort
category is still A. This would equal a floor temperature
of 20 °C and a dimensioned room temperature of
28 °C. The dimensioned room temperature must be
below 26 °C and similarly above a floor temperature
of 20 °C in order to reach comfort class B. Hence, the
vertical air temperature difference will in practice not
cause a indoor climate below category A.
As the pictures below show, different emitter systems
provide different temperature gradients in a room.
Clearly, a radiant heating system in the floor provides
a temperature gradient closest to the ideal. Similarly,
a radiant cooling system in the ceiling provides a
temperature gradient closest to the ideal.
0
0,5
1
1,5
2
2,5
3
2 4 6 8 10
A
B
ΔT floor surface room
Verticalairtemperaturedifference[K]
0,1 - 1,1 m
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13. Thermal transfer coefficient
The thermal transfer coefficient is an expression of how
large an effect per m2
the surface is able to transfer to
the room, per degree of the temperature difference
between the surface and the room. The figure below
shows the thermal transfer coefficient for different
surfaces for heating and cooling respectively.
Due to natural convection, the floor provides the
best thermal transfer coefficient for heating while the
ceiling provides the best thermal transfer coefficient for
cooling.
Dew point limitations
In order to secure that there is no condensation on the
surface of the emitter in the room the supply water
temperature should be controlled so that the surface
temperatures of the emitter always is above dew point.
In the diagram below, the dew point temperatures can
be found under different levels of relative humidity
(RH):
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
40 45 50 55 60 65 70 75 80
Dewpointtemperature[°C]
Relative humidity RH [%]
Room temp. 26 °C
Room temp. 25 °C
Room temp. 24 °C
Room temp. 23 °C
All emitter systems, whether it is pure air-based,
radiators or pure radiant systems, are bounded by their
ability to transfer energy. The capacity of any radiant
emitter systems is limited by the heat flux density, which
differs depending on the location of the emitter, i.e.
floor, wall or ceiling. The heat flux density can be used
to calculate the capacity of the emitter, also known as
the thermal transfer coefficient. Specifically regarding
cooling, any radiant emitter will need to work within the
dew point limitations in order to avoid moisture on the
surface and within the construction.
Heat flux density
The ability of a surface to transfer heating or cooling
between the surface and the room, is expressed by the
heat flux density. According to EN 1264/EN 15377,
the values below can be used to express the heat flux
density.
Floor heating, ceiling cooling: q = 8.92 (θs,m
- θi
)1.1
Wall heating, wall cooling: q = 8 (| θs,m
- θi
|)
Ceiling heating: q = 6 (| θs,m
- θi
|)
Floor cooling: q = 7 (| θs,m
- θi
|)
Where
q is the heat flux density in W/m2
θs,m
is the average surface temperature (always limited
by dew point)
θi
is the room design temperature (operative)
4. Capacity and limitations of radiant emitter
systems
10
5
0
15
Surface heating and cooling
Floor Ceiling Wall
Heating
Cooling
[W/m2
K]
Thermaltransfercoefficient
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14. Emitter surface and humidity
Design temperatures for cooling systems are specified
according to the dew point. The dew point is defined by
the absolute humidity in the room and can be estimated
from the relative humidity RH and the air temperature.
The cooling capacity of the system is defined by the
difference between the room temperature and the mean
water temperature.
Often standard design parameters for cooling systems
are an indoor temperature of 26 °C and a relative
humidity of 50%. At the dew point, condensation
will occur on the emitter surface. In order to avoid
condensation, the emitter surface temperature has to be
above the dew point temperature.
For radiant floor cooling a minimum surface temperature
of 20 °C is required, which means that only when the
relative humidity exceeds 70% in the room, the risk
of condensation occurs, because that corresponds to
a relative humidity of 100% at the emitter surface.
Radiant cooling from the ceiling is limited by the radiant
asymmetry between the surface of the emitter and the
room temperature recommendation is that it should not
exceed more than 14 K. For standard conditions (26 ºC,
50% RH) the surface of the emitter usually reaches the
dew point before the radiant asymmetry limit.
Distribution pipes and manifolds
In any cooling system where you have distribution pipes
or manifolds you have to be aware of that these parts
of the system also have a risk of condensation because
they sometime operates below the dew point. Insulation
of distribution system is often necessary in order to
avoid condensation.
Design temperature
The design supply water temperature of the system
depends on the type of surface used, the design indoor
conditions (temperature and relative humidity) and the
cooling loads to be removed. It should be calculated to
obtain the maximum cooling effect possible from the
system.
The capacity and mean water temperature for radiant
floor cooling depends on the floor construction, pipe
pitch and surface material. To have the highest possible
capacity of the system you should design your floor
construction so the surface temperature is equal to the
minimum temperature of 20 °C.
The capacity and mean water temperature for radiant
cooling from the ceiling is calculated, or can be read
directly, in the capacity diagram of the cooling panels.
To have the highest possible capacity of the system you
should design as close to the dew point as possible.
Theoretical capacities of
embedded radiant cooling
Taking both ISO 7730 (surface temperatures, radiant
asymmetry, and down draught) and the dew point
limitations into account, the following surface
temperature limitations exist.
Surface temperature limitations
With these surface temperature limitations in mind, the
maximum capacities of different radiant emitter systems
can be calculated. The results are shown in the figure
below.
Maximum heating a cooling capacities
In theory, the highest heating capacity can be achieved
from the wall. Since space is limited due to windows
and other things hanging on the wall, the real heating
capacity from walls is significantly reduced. Hence, the
biggest capacity can be achieved by heating from the
floor, and cooling from the ceiling. In practice, either
a floor system or a ceiling system is installed and used
for both heating and cooling. A floor system should
be chosen if the heating demand is dominant and a
ceiling system should be chosen if the cooling demand
is dominant.
35
25
15
45
30
20
40
Floor Ceiling Wall
Heating
Cooling
Parimeter
Temperature[°C]
80
40
0
120
60
20
100
140
180
160
200
Floor Ceiling Wall
Heating
Cooling
Parimeter
HeatingandCoolingCapacity[W/m2
]
14 UPONOR · FREE COOLING G UIDE

15. 5. Ground heat exchangers
Ground conditions
When planning the use of ground heat exchangers,
the ground conditions are of fundamental importance.
Determining the ground properties, with respect to
the water content, the soil characteristics (i.e. thermal
conductivity), density, specific and latent thermal
capacity as well as evaluating the different heat and
substance transport processes, are basic pre-requisites
to determine and define the capacity of a ground heat
exchanger. The dimensioning has a significant impact
on the energy efficiency of the heat pump system.
Heat pumps with a high capacity have unnecessary
high power consumption when combined with a poorly
dimensioned heat source.
With a higher water concentration in the ground, you
get a better system capacity. Horisontal collectors are
hence depending on the ground’s ability to prevent rain
water from mitigating downwards due to gravitation.
The smaller the corn size in the soil, the better the
ground can prevent rain water from gravitation. Hence
clay will provide a better performing ground heat
exchanger than sand. Vertical collectors are depending
on being in contact with ground water. Hence the depth
of ground water levels has an important impact on the
performance of a vertical ground heat exchanger.
In addition to the water concentration, different ground
types have different thermal conductivity. For example
rock has a higher thermal conductivity than soil, so
ground conditions with granite or limestone will give a
better performing ground heat exchanger than sand or
clay.
Soil type
Thermal conductivity
(W/m K)
Clay/silt, dry 0.5
Clay/silt, waterlogged 1.8
Sand, dry 0.4
Sand, moist 1.4
Sand, waterlogged 2.4
Limestone 2.7
Granite 3.2
Source: VDI 4640
15UPO NO R · FREE COOLING GUIDE

16. Ground heat exchangers
With ground heat exchangers, a distinction is made
between horisontal and vertical collectors. These can be
further classified as follows:
Horisontal:
• Horisontal or surface collectors
• Energy cages
Vertical:
• Boreholes
• Energy piles and walls
The suitability of the different collectors depends on the
environment (soil properties and climatic conditions),
the performance data, the operating mode, building
type (commercial or private), the space available and
the legal regulations.
Horisontal collectors
Collectors installed horisontally or diagonally in the
upper five meters of the ground (surface collector).
These are individual pipe circuits or parallel pipe
registers which are usually installed next to the building
and in more rare cases under the building foundation.
Energy cages
Collectors installed vertically in the ground. Here, the
collector is arranged in a spiral or a screw shape. Energy
cages are a special form of horisontal collectors.
Boreholes
Collectors installed vertically or diagonally in the
ground. Here one (single U-probe) or two (double
U-probe) pipe runs are inserted in a borehole in
U-shape or concentrically as inner and outer tubes.
Energy piles
Collectors build into the pile foundations that are
used in construction projects with insufficient load
capacity in the ground. Individual or several pipe runs
are installed in foundation piles in a U-shape, spiral or
meander shape. This can be done with pre-fabricated
foundation piles or directly on the construction site,
where the pipe runs are placed in prepared boreholes
that are then filled with concrete. Most often energy
piles are used for larger commercial buildings.
16 UPONOR · FREE COOLING G UIDE

17. Ground temperature profile
The figure below shows a generic temperature profile in
the ground for each season during the year.
The closer to the ground surface, the higher the
influence from the outside temperature and solar
radiation. Hence not surprisingly, the highest
temperatures are found in late summer and the
lowest temperatures in late winter. The reason for the
temperatures being higher in late autumn than late
spring, has to do with the ground’s ability to store
energy. After a warm summer period, the ground
remains relatively warm during the autumn. Ground
temperatures stabilize below 10-15 m. It is clear from
these ground temperature profiles that the cooling
capacity is higher below 15 m. Hence vertical collector
systems provides a better cooling capacity than
horisontal collector systems.
Primary supply temperatures
The temperatures mentioned in the previous section
are often referred to as the undisturbed ground
temperature. Depending on the thermal resistance
between the collector and the surrounding ground, the
temperature of the fluid in the collector will be higher
than the surrounding ground.
0 20
20
0
15
10
5
0 2010 155
10 155
1. February
1. May
1. November
1. August
Temperature (earth’s surface) [°C]
Depthinsoil[m]
Temperature (depth) [°C]
Dimensioning of ground heat
exchangers for free cooling
The first thing to decide is whether the ground heat
exchanger shall be used for heating only or for both
heating and cooling. As demonstrated in this guide,
new built low energy houses will often have substantial
cooling loads. It is therefore highly recommendable to
use the ground heat exchanger for free cooling in the
summer period. A combined use for heating and cooling
also balances of the ground temperature during the
year and leaves the ground environment undisturbed.
Existing guidelines for dimensioning ground heat
exchangers are typically based on the peak load for the
heating demand. But in order to ensure that adequate
cooling capacity is available in the summer season, it
is recommend doing a design check for the maximum
cooling load as well.
Dimensioning for the heat load should be done based
on the peak load for space heating plus the domestic
hot water need. As a heat pump is used for covering
the heat load, the COP of the heat pump on the
coldest day (design day) should be applied in the
design calculation. In addition to this, the specific
characteristic of the chosen heat exchanger and the
thermal conditions in the ground must be taken into
account.
Dimensioning for the cooling load should be done
based on valid information of the maximum cooling
load in the building. Free cooling operates without a
heat pump. It is therefore vital that the thermal capacity
of the ground heat exchanger is able to fully cover the
max cooling load (no COP is included). In residential
buildings in Northern Europe the cooling need will
normally be covered with the capacity derived from
the heating requirements. But a design check is always
recommended.
In special cases in residential buildings and typically in
office buildings, the cooling need will be dominant and
thus the design driver. In such case vertical collectors
are normally recommended as the deeper ground
temperatures are sufficiently stable and independent of
surface temperature and solar radiation. If a horizontal
system is chosen, the space requirements can be a
capacity limitation. Designing for inadequate cooling
capacity on the warmest summer days may then
be necessary compromise, but should be evaluated
carefully.
17UPO NO R · FREE COOLING GUIDE

18. Dimensioning examples
In order to dimension ground heat exchangers cer-
tain information has to be considered. First of all an
estimation of the physical properties of the ground is
needed. Normally its possible to obtain local ground
data (thermal conductivity etc.) from local databases
or authorities. The figures below show the capacity for
different collectors.
Horisontal collectors Energy cage Vertical collectors
Pipe size 25, 32 and 40 mm Normal 32 mm XL 32 mm 40 mm
Capacity cooling 7-28 W/m2
800-1120 W 1000-1500 W 30-70 W/m
Dimensioning temperature,
supply/return
17-20 °C 14-17 °C 10-13 °C 10-13 °C
*) Energy cage; normal height is 2.0 m, and
XL height 2.6. Required depth is 4 m.
Flow and pressure drop in the collector
When the cooling need is defined, the flow can be
calculated. When using ground collectors, the water
used has to be mixed with anti-frost liquid. Hence,
the specific heat capacity and density in the brine is
Cooling need
[kW]
Ethanol Monoethylenglyciol Propylenglycol
Flow [kg/s] Flow [l/s] Flow [kg/s] Flow [l/s] Flow [kg/s] Flow [l/s]
2 0.16 0.15 0.18 0.19 0.17 0.18
3 0.24 0.23 0.27 0.28 0.26 0.27
4 0.32 0.31 0.36 0.38 0.34 0.36
5 0.40 0.38 0.45 0.47 0.43 0.45
6 0.48 0.46 0.54 0.56 0.51 0.54
different from the physical properties of pure water.
The table below shows the required flow of often used
brines for providing different cooling capacity.
When calculation the pressure loss in the collector the
flow is divided equally up in the number of loops. For
vertical collectors the total pressure loss is normally
very low hence the pressure is equalized and it is only
the pressure loss in the feeding pipe has an influence.
For horisontal collectors and partly energy cages
the pressure loss has to be calculated in order to be
sure that the pump will be able to circulate the water
through the collector and the cooling exchanger
including manifolds and valves.
Example: 4 kW installations
Horisontal collector extraction
power
15 W/m2
Liquid Monoethylenglycol
Total flow 0.38 l/s, 1.37 m3
/h
Diameter of collector Ø 32 mm
In the diagram below, the pressure loss in the
ground collector should be maximum 34 kPa at the
dimensioning conditions, and the ground collector
should be dimensioned so that the pressure loss in each
loop is less than 34 kPa.
Pump diagram
Available pressure for the primary circuit.
CP1
CP2
0 0.5 1 1.5 2 2.5 3
50
40
30
20
10
0
Pressure loss [kPa]
Rate of flow [m3
/h]
18 UPONOR · FREE COOLING G UIDE

19. 6. Free cooling in combination with different heat
sources
Heating mode, the free cooling is deactivated Cooling mode, the free cooling is activated
The illustrations below shows a ground heat exchanger
combined with a radiant system in heating mode and
cooling mode. In this example a ground sourced heat
pump is providing heating to domestic hot water
(DHW), space heating, and for heating up the incoming
ventilation air. This could of course be utilized with
other heat sources such as boilers or district heating.
Free cooling is provided through a special pump and
exchanger group (see chapter 8) that supplies cold
water/brine from the ground heat exchanger directly to
the radiant emitter system and possibly the incoming
ventilation air. In cooling mode, the heat pump will only
be active for domestic hot water generation.
As one can see from the grey connection lines the pump
and exchanger group is not active in heating mode.
Similarly, the connection lines from the heat pump (or
any other heat source) to the emitter systems are in-
active in cooling mode.
If a boiler or district heating system is used as heating
source, the ground heat exchanger will only work during
cooling (also known as a bivalent system). If a ground
source heat pump is used as heat source, the ground
ground heat exchanger will work both during heating
and during cooling (also known as a monovalent
system).
19UPO NO R · FREE COOLING GUIDE

20. Embedded emitters are the key to any radiant system.
In order to have an energy efficient and comfortable
solution, the emitter system has to be designed to
the construction but also to the task it has to solve.
There are many types of constructions for floor, wall
and ceilings. Uponor offers emitters that can meet the
requirements of all types of installations. All emitters
are able to provide heating and cooling. However, some
emitters are more efficiently than others. The most
efficient cooling system is placed in the ceiling, but the
heating efficiency is lower whereas an emitter system in
Capacity of different radiant
emitter systems
In order to calculate the capacity of the radiant emitter,
it is important to know the construction in which the
embedded emitter is integrated, including the surface
material on top of the construction. In general, there are
three factors that influence on the capacity of a radiant
emitter system:
• Thermal resistance in the surface construction RB
• Pipe pitch, i.e. the distance between the pipes T
• Thermal conductivity in the construction material
In practice, this means that when designing the floor
construction, the performance of the radiant system can
be optimised by choosing the right construction, pipe
layout and surface material.
Floor installation Wall installation Ceiling installation
the floor has the highest heating efficiency, but with a
lower cooling efficiency.
Another important factor is the supply water
temperature. Radiant emitter systems operate on a
relatively low temperature for heating, and a relatively
high temperature for cooling. A radiant system should
be designed for the lowest possible temperature for
heating and the highest possible temperature for
cooling. This secures a heating/cooling system with
high energy efficiency and optimal conditions for the
heating and cooling supply.
Example: floor construction
7. Choosing and dimensioning the radiant emitter
system
20 UPONOR · FREE COOLING G UIDE

21. Pipe pitch, i.e. distance between the
pipes
The pipe pitch, i.e. the distance between the pipes in
the embedded construction, not only has an influence
on the capacity, but also on how equal the surface
temperature is. This is especially important from a
comfort perspective.
The diagram shows the capacity of a concrete floor
construction with  =1.8 W/(mK), and with different
kinds of surface material. The diagram illustrates the
variation of the capacity depending on the pipe pitch.
A short distance between the pipes, gives a higher
capacity and vice versa. For a combined heating and
cooling system, it is recommended to use a relatively
small distance  300 mm between the pipes, in order
to utilise free cooling and maintain an even surface
temperature.
Thermal conductivity in the construction
The thermal conductivity in the construction has an
effect on the system’s ability to distribute heating and
cooling in the thermal mass. A construction with a low
thermal conductivity requires a smaller pipe pitch, in
order to obtain an equal surface temperature variation.
RλB
= 0
RλB
= 0.05
RλB
= 0.10
RλB
= 0.15qCN
(RλB
= 0.15)
qCN
(RλB
= 0)
ΔθCN
Y = Specific thermal output qc
[W/m2
]
X = Temperature difference between
room and cooling medium [θc
K]
45
40
35
30
25
20
15
10
0.1 0.15 0.2 0.3 0.4 0.50.25 0.35 0.45
Thermaloutputq[W/m2
]
Pipe spacing T [m]
θm
15.5 °C,
14 mm parquet
θm
15.5 °C,
7 mm parquet
θm
15.5 °C,
10 mm tiles
θm
18.5 °C,
14 mm parquet
θm
18.5 °C,
7 mm parquet
θm
18.5 °C,
10 mm tiles
Floor surface temperature limit 20 °C
Thermal resistance in the surface
construction
The thermal resistance in the surface construction has a
big influence on the performance of the emitter. In the
diagram, an example of a cooling curve where different
thermal resistance values from 0.00 to 0.15 m2
K/W are
shown. The curve shows that higher resistance gives a
lower capacity. All constructions with embedded radiant
emitter systems will have a surface resistance that has to
be considered. In order to get the highest efficiency, the
resistance value has to be as low as possible.
Field of characteristic curves of a cooling system
For dry constructions, high performance material like
heat distribution plates in aluminium or similar are used
to ensure optimal heating and cooling distribution.
21UPO NO R · FREE COOLING GUIDE

22. Surface material
Tiles 10 mm, = 1.0 W/mK
Surface material
Wood 14 mm parquet, = 0.014 W/mK
Installation
principle
Cooling effect
q [W/m2
]
θm
15.5 °C
Cooling effect
q [W/m2
]
θm
18.5 °C
Cooling effect
q [W/m2
]
θm
15.5 °C
Cooling effect
q [W/m2
]
θm
18.5 °C
Wet floor
installation
42 40 33 24
Installation
integrated in
construction
42 40 33 24
Installation on the
joists
28 20 27 19
Dry floor
installation
28 20 27 19
Installation
between the joists
24 17 18 14
Floor
installation
Radiant floor constructions and
capacity
Radiant floor systems are far more common than
ceiling or wall systems, and can be used for cooling and
heating. A radiant floor system can be installed in wet
constructions using concrete and screed, and in dry
constructions with heat emissions plates.
A radiant floor has a cooling capacity of up to 42 W/m2
limited by a surface temperature of 20 °C. The most
efficient installation is in a wet construction with con-
crete or screed, because of its high heat conductivity,
using a relatively short distance between the pipes, and
a surface material with a low thermal resistance.
In the figure below, an overview of the capacity in
the most common floor installations is shown with
mean water temperatures of 15.5 °C and 18.5 °C
corresponding to supply temperatures of 14 °C and
17 °C with a T of 3 K over the emitter loops. Figures
are based on a room temperature of 26 °C and a surface
temperature of 20 °C.
22 UPONOR · FREE COOLING G UIDE

23. Wall
installation
Installation
principle
Cooling effect
q [W/m2
]
θm
15.5 °C
Cooling effect
q [W/m2
]
θm
18.5 °C
Cooling effect
q [W/m2
]
θm
15.5 °C
Cooling effect
q [W/m2
]
θm
18.5 °C
Cooling effect
q [W/m2
]
θm
15.5 °C
Cooling effect
q [W/m2
]
θm
18.5 °C
Dry wall
installation
45 32
Wet wall
installation
60 45
Stud wall
installation
42 34
Radiant wall constructions and
capacity
Radiant wall systems are typically used as a supplement
to floor and ceiling emitter systems for rooms
with a higher need for cooling/heating. Instead of
dimensioning the floor or ceiling system according to
the room with the highest peak load, it can be designed
according to the average and the peak room(s) can be
supplemented with a wall emitter.
A radiant wall system will be limited by the architecture
and by the furnishing. Radiant wall systems have a
cooling capacity of up to 60 W/m2
(active area) limited
Surface material
Plaster 10 mm,  = 0.7 W/mK
Surface material
Plaster 11 mm,  = 0.24 W/mK
Surface material
Plaster 11 mm,  = 0.23 W/mK
by a surface temperature of 17 °C, in order to be within
the limits of radiant asymmetry and to prevent draught.
In the figure below, an overview of the capacity of the
most common wall systems is shown with mean water
temperatures of 15.5 °C and 18.5 °C corresponding
to supply temperatures of 14 °C and 17 °C with a T
of 3 K over the emitter system. Figures are based on a
room temperature of 26 °C and a surface temperature
of 20 °C .
23UPO NO R · FREE COOLING GUIDE

24. Installation
principle
Cooling effect
q [W/m2
]
θm
15.5 °C
Cooling effect
q [W/m2
]
θm
18.5 °C
Cooling effect
q [W/m2
]
θm
15.5 °C
Cooling effect
q [W/m2
]
θm
18.5 °C
Cooling effect
q [W/m2
]
θm
15.5 °C
Cooling effect
q [W/m2
]
θm
18.5 °C
Wet ceiling
installation
75 55
Dry ceiling
installation
59 42
Suspended
ceiling
installation
97 67
Ceiling
installation
Radiant ceiling constructions
and capacity
Radiant ceiling systems are the most efficient systems
for cooling, but can also be used for heating. Ceiling
systems have originally been developed for office
environments, but are also available for residential
constructions using wet plaster or dry gypsum panels.
Radiant ceiling systems have a cooling capacity of up
to 97 W/m2
. It is important to note that especially for
ceiling cooling, the surface temperature of the system
is in peak often very close to the dew point. Special
attention has to be taken for adequate dew point
control.
In the figure below, an overview of the capacity in
the most common ceiling systems is shown, with
mean water temperatures of 15.5 °C and 18.5 °C
corresponding to supply temperatures of 14 °C and
17 °C with a T of 3 K over the emitter system. Figures
are based on a room temperature of 26 °C and a surface
temperature of 16 °C.
Capacity diagrams
Uponor offers a wide range of embedded emitter
systems adapted to different kinds of constructions in
the floor, wall or ceiling. Whenever the choice of system
has been selected, detailed diagrams can be used in
order to make the planning of the capacity. The diagram
and example on next page shows a floor construction
with the cooling and heating output of the emitter
system.
Dimensioning diagram for cooling
Analogue to dimensioning for heating, the following
parameters must be considered:
1. Cooling effect of the radiant area qc
[W/m2
]
2. Thermal resistance in the surface construction RB
[m2
K/W]
3. Pipe pitch, i.e. centre distance between the pipes T
[cm]
4. Difference between room temperature and mean
water temperature θc.
= θi
- θc
[K]
5. Recommended minimum surface temperature
(20 °C)
6. Difference between room temperature and surface
temperature θv
- θr, m
[K]
If three of the parameters above are known, the
remaining parameters can be calculated using the
diagram to the right.
Surface material
Plaster 10 mm,  = 0.7 W/mK
Surface material
Plaster 11 mm,  = 0.23 W/mK
Surface material
Plaster 11 mm,  = 0.24 W/mK
24 UPONOR · FREE COOLING G UIDE

25. 0,15
0,05
0,10
T qH ΔθH,N
cm W/m2 K
10 98,6 15,9
15 96,3 18,1
20 93,0 20,3
25 87,3 22,0
30 81,3 23,6
0
0,05
0,10
20
100
40
60
80
0,15
T qC ΔθC,N
cm W/m2 K
10 34,8 8
15 39,8 8
20 27,5 8
25 24,5 8
0
20
40
60
80
0
ΔθH
= θH
Ðθi
= 15 K
T 15
T 25
T 30
T 20
T 10T 15
T 20
T 25
T 10
T 15
T
20
T
25
Heating
Cooling
T 30
ΔθC
= θi
ÐθC
= 4 K
10 K
8 K
6 K
Dimensioning example for cooling
Estimating the dimensioned supply water temperature θV, Ausl.
Given: qc
= 29 W/m²
 θi
= 26 °C
RB
= 0.05 m² K/W
Chosen pipe pitch = Vz 15
 T: θv
- θH
= 2 K
Read from the diagram: θc
= 12 K
 θr, m
- θi
= 3.9 K
Calculated: θr, m
= i
- 4.3 K
 θr, m
= 21.7 °C
(O.K., as this is above the recommended
minimum surface temperature (20 °C)
θV, calc.
= θi
- θc
- (θv
- θR
)/2
θV, calc.
= 26 - 9 - 2/2
θV, calc.
= 16 °C
ThermaloutputheatingqH
[W/m2
]ThermalresistanceRB
[m2
K/W]
Thermaloutputcoolingqc
[W/m2
]
Note: The required cooling effect can only be achieved
if the median surface temperature and the dimensioned
supply temperature are above the dew-point. In order
to avoid condensation, a supply water controller such as
Uponor Climate Controller C-46 is needed.
25UPO NO R · FREE COOLING GUIDE

26. The purpose of a control systems is to keep one
or more climate parameters within specified limits
without a manual interference. Heating and cooling
systems require a control system in order to regulate
room temperatures during shifting internal loads and
outdoor temperatures. Good control systems adapt
to the desired comfort temperatures while minimising
unnecessary energy use.
In residential buildings two different types of controls
principles are common; zone control and individual
room control.
In a zone control system, the temperature is
controlled in a common zone consisting of several
rooms and heating and cooling is supplied evenly to
the full zone. Not all national building codes allow
zone control systems as they have major shortfalls with
comfort as well as energy consumption.
In low-energy buildings there will in particular be high
variations in the individual room heating and cooling
loads (see figure 5.2). This means that lack of individual
room control causes the room with the highest demand
to determine the heating or cooling supply to a full
zone, resulting in over temperatures and unnecessary
high energy consumption.
An individual room control system is much
preferable in order to meet room specific load variations
and individual comfort requirements. Due to high
variations in the individual room loads in low-energy
buildings, an individual room control system is also
required to minimise the energy consumption.
The basic principle in an individual room control system
is that a sensor measures the room temperature and
regulates the heating or cooling supplied to the space
controlled in order to meet a user defined temperature
set point. The most well-know examples are radiators
with thermostatic valves and underfloor heating systems
with room thermostats.
In addition, room by room regulation provides the
possibility to shut down cooling in a specific room, such
as a bathroom or a room without cooling loads.
21°C
21°C
21°C
18°C
18°C
22°C
22°C 20°C21°C
Typical desired temperature (set points) in a single family house. Typical variation between individual room heat demands in a
low-energy house.
Regulation and control
Living room Kitchen
Room 1
Bedroom Bath 1 Room 3 Entrance Bath 2
Room 2
26 UPONOR · FREE COOLING G UIDE

27. The self-regulating effect in
underfloor heating
Radiant floor heating and cooling benefits from a
significant effect called ”self control” or “self regulating
effect”. The self regulating effect occurs because the
heat exchange from the emitting floor is proportional
to the temperature difference between the floor and
the room. This means that when room temperature
drifts away from the set point, the heat exchange will
automatically increase.
The self regulating effect depends partly on the
temperature difference between room and floor surface
and partly on the difference between room and the
average temperature in the layer, where the pipes are
embedded. It means that a fast change of the operative
temperature will equally change the heat exchange.
Due to the high impact the fast varying heat gains
(sunshine through windows) may have on the room
temperature, it is necessary that the heating system can
compensate for that, i.e. reduce or increase the heat
output.
Low-energy houses will largely benefit from the self
regulating effect, because the temperature difference
between floor and room will be very small. A typical
low-energy house has on average for the heating
season a heat load of 10 to 20 W/m² and for this size of
heat load, the self regulating effect will be in the range
of 30 - 90%.
Self-regulating effect. UFH/C outputs for different temperatures
between room and floor surface.
Functional description of
Uponor Control System
Individual room control with traditional
on/off functionality
For a radiant floor heating and cooling system, the
control is normally split up in a central control and
individual room controls. The central control unit is
placed at the heat source. It controls the supply water
temperature according to the outside temperature
based on an adjustable heat curve. The individual room
control units (room thermostats) are placed in each
room and controls the water flow in the individual
underfloor heating circuit by ON/OFF control with a
variable duty cycle. Its done according to the set-point
by opening and closing an actuator placed at the central
manifold.
Individual room control with DEM
technology
Uponor’s Dynamic Energy Management control
principle is an advanced individual room system based
on innovative technology and an advanced self learning
algorithm. Instead of a simple ON/OFF control, the
actuators on the manifold supplies the energy to each
room in short pulses determined based on feedback
from the individual room thermostats.
Uponor Control System DEM is self learning and will
remember the thermal behavior of each room. This
ensures an adequate and very accurate supply of
energy, which means better temperature control and
energy savings.
Typical behaviour in a heavy floor construction, where Uponor
DEM technology ensures that a minimum of energy is lost to the
construction. Compared with traditional on/off regulation, saving
figures between 3-8% can be obtained.
19
20
21
22
23
24
25
26
27
°C
c
b
a
= Floor surface temperature
= Room temperature
a heating = 19.1 W/m2
b heating = 13.9 W/m2
c cooling = -10.5 W/m2
Time
Uponor DEM
technology
Saved energy when
using Uponor DEM technology Actuator on/off
Lost energy when
using Uponor DEM technology
Higher
temperature
+
-
Lower
temperature
Thermostat set
point 20°C
Time
27UPO NO R · FREE COOLING GUIDE

28. Zone control
When using zone control for a radiant floor heating
and cooling system, the central controller is normally
placed at the heat source. It controls the supply water
temperature according to the outside temperature
based on an adjustable heat curve. The manifold system
Simple zone control, the central controller provides a regulated supply
temperature based on the outdoor/indoor temperature.
M
C-46
230 V AC
230 V AC
24 V DC
M
C-56
C-56
C-56
I-76
H-56
T-75
T-55T-54
has no actuators and normally the system works at a
constant flow with temperature regulation based on
a reference thermostat is placed in one of the main
rooms.
Individual room control, the central controller provides a regulated
supply water temperature based on the outdoor/indoor temperature and
the room thermostat controls the room temperature by using actuators.
C-46
M
230 V AC
28 UPONOR · FREE COOLING G UIDE

29. The Uponor Pump and exchanger group, EPG6,
is designed for a separate cooling supply and
temperature control for ground source free
cooling. The EPG6 is pre-mounted and ready
to install in the installations. Together with
the Uponor ground collectors it is ready
to provide free cooling for radiant emitter
systems.
The EPG6 can be integrated in HVAC
installations for applications a separate supply
of cooling needs to be provided through a
heat exchanger (e.g. from a ground collector).
The EPG 6 is controlled by Uponor Climate
Controller C-46, which is able to adjust the
secondary temperature supplied to the emitter
8. Uponor Pump and exchanger group (EPG6) for
ground sourced free cooling
system and interact with the Uponor Control
System used to control the emitter system.
Uponor Climate Controller C-46 is also able to
control the temperature according to the dew
point, in order to prevent condensation.
The primary side of the system is driven by
a circulation pump, to circulate the fluid
in the brine circuit and a 3-way mixing
valve for controlling the primary flow, in
order to maintain the correct temperature
on the secondary side. The exchanger that
exchanges the brine from the ground circuit
with the water in the emitter system is
designed for a capacity up to 6 kW.
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
10
10
11
11
Secondary circlet,
to emitter system
Primary side, ground collector
or other cooling supply
Component overview
Primary side
The primary side of the system (ground collector) is
connected to the EPG6 and will work as the heat sink.
The mixing valve (1) will adjust the flow of the primary
side and is controlled by the Uponor Climate Controller
C-46 (10), which opens and closes the valve to the
adjusted supply temperature on the secondary side
measured by the supply sensor (7). The primary pump
(2) will circulate the fluid in the brine circuit through
the exchanger (4) and will shut down when there is no
request from the secondary control system. The filling
and air valve (3) is used to fill up the primary system
with brine. Connection to an expansion tank and safety
valves can be done on the connection valve (9).
Secondary side
The secondary ball valves (5 and 6) are shutting down
the secondary side of the system, and have a ball
valve (5) including a check valve to prevent backflow
in the system. The blind piece (8) can be replaced
by a circulation pump, if no other pump is used for
the secondary side. The secondary pump has to be
connected to the Uponor Climate Controller C-46 (10).
3 way mixing valve Kvs
7 m3
/h
Primary circulation pump Grundfos Alpha 2L 26-60
Filling and air valve G ¾”
Heat exchanger 6 kW SWEP ESTH x 40/1P-SC-S 4 x ¾”
Ball valve with integrated check valve and thermometer Rp 1”
Ball valve with integrated thermometer Rp 1”
Sensor pocket (supply)
Blind piece 180 mm G 1¼” for secondary circulation pump
Filling valve G ¾”
Uponor Climate Controller C-46
Primary connection Rp 1¼”
29UPO NO R · FREE COOLING GUIDE

30. Dimensions
Pump diagram
Available pressure for the primary circuit
Rp 1¼
360
580
Rp 1 Rp 1
125
230
80
Rp 1¼
CP1
CP2
0 0.5 1 1.5 2 2.5 3
50
40
30
20
10
0
Pressureloss[kPa]
Flow rate [m3
/h]
30 UPONOR · FREE COOLING G UIDE

31. Control principle
Controls is required for the primary system as well as the
secondary system.
Since the primary control of the heating mode is
separated from the primary control of the cooling mode,
the change-over between heating and cooling must
be defined. This can be done either automatically if a
communication interface can be setup between the
Uponor Climate Controller C-46 and the heat source or
through a manual switch if it is not possible to setup a
communication interface.
Because a radiant emitter system can act for both
heating and cooling, the secondary system can be
controlled by one system as described below.
Secondary control – heating and cooling
For the secondary control of the emitter system,
Uponor recommends to apply individual room control,
in order to provide energy efficiency and comfort. The
individual control system also secures that cooling can
be deactivated in single rooms/zones, e.g. in bathrooms
where cooling might not be required. The Uponor
Control System offers a long range of benefits for the
user and can be integrated with the primary controller
for cooling, Uponor Climate Controller C-46.
Primary control – cooling
The primary control of the cooling system is provided by
the EPG6 which includes the Uponor Climate Controller
C-46 that manages:
• the supply temperature of the system
• pump management of primary and secondary
pumps
• change-over between heating and cooling
• dew point management with up to six wireless dew
point sensors (Uponor Relative Humidity Sensor
H-56)
In order to eliminate the
risk of condensation on the
emitter surface, dew point
management is an essential
part of the cooling system.
The relative humidity sensors
measure the relative humidity
and the temperature in the
room, and Uponor Climate
Controller C-46 uses the data
to calculate the dew point.
Thereby, it is able to secure
that the supply water temperature never gets too low,
and that no condensation will occur on the emitter
surface.
C-56 I-76
T-75H-56 T-54 T-55
31UPO NO R · FREE COOLING GUIDE

32. Hydraulic change-over between heating
and cooling
Uponor recommends using a diverting valve in the
secondary heating/cooling distribution system, which
opens and closes when changing between heating and
cooling. The diverting valve is controlled by the Uponor
Climate Controller C-46 either directly through a 24 V
actuator or through a relay for a 230 V actuator. The
diverting valve is activated by the change-over signal
between the heating and cooling modes.
Heating mode
In heating mode, the free cooling system is deactivated.
Hence, no pumps are running and the diverting valve is
closed (the flow goes straight through).
Cooling mode
In cooling mode, the free cooling system is activated.
Hence, pumps are running and the diverting valve is
open. An internal circuit is secured for the heat source
for producing domestic hot water.
32 UPONOR · FREE COOLING G UIDE

33. TW
M
6
4
3
1
2
3
4
5
6
7
8
7
9
5
8
1
2
9
Installation examples
Brine to water heat pump with Uponor EPG6
The system diagram illustrates a Uponor free cooling
installation using a ground collector and Uponor EPG6
in combination with a brine to water heat pump for
space heating and domestic hot water.
The EPG6 (3) is connected to a Uponor ground collector
(1) on the primary side of the free cooling installation. If
more than one ground loop is installed, a manifold can
be used to connect the ground loops.
The secondary side of the EPG6 is connected to the
heating pipe system before the manifold of the radiant
system (4).
A diverting valve (7) is used to switch the flow direction
in the hydraulic system between heating and cooling
(diverting valve to open when cooling is activated).
When switching between heating and cooling, the heat
pump must be in a position where it only produces
domestic hot water (typically “summer mode” can be
used).
The Uponor Climate Controller C-46 can send an
external signal to the heat pump when switching
between heating and cooling or it can be done
manually with a relay switch. Contact the heat pump
manufacturer in order to check the possibilities.
Ground collector
Brine to water heat pump
Uponor EPG6 with Uponor Climate Controller C-46
Radiant emitter system
Buffer tank
Domestic hot water tank
Diverting valve
Non return valve
Secondary circulation pump
33UPO NO R · FREE COOLING GUIDE

34. M
6
2
5
8
7
4
1
3
1
2
3
4
5
6
7
8
Condensing boiler with Uponor EPG6
The system diagram illustrates a Uponor free cooling
installation using a ground collector and Uponor EPG6
in combination with a gas/oil boiler for space heating
and domestic hot water.
The EPG6 (3) is connected to a Uponor ground
collector (1) on the primary side of the free cooling
installation. If more than one ground loop is installed, a
manifold can be used to connect the ground loops.
The secondary side of the EPG6 is connected to the
heating pipe system before the manifold of the radiant
system (4).
A diverting valve (7) is used to switch the flow direction
in the hydraulic system between heating and cooling
(diverting valve to open when cooling is activated).
When switching between heating and cooling, the boiler
must be in a position where it only produces domestic
hot water (typically “summer mode” can be used).
The Uponor Climate Controller C-46 can send an
external signal to the boiler when switching between
heating and cooling or it can be done manually with a
relay switch. Contact the boiler manufacturer in order to
check the possibilities.
In the example below, a solar collector is supporting the
boiler for space heating and domestic hot water but is
not interacting with the cooling system.
Ground collector
Condensing boiler
Uponor EPG6 with Uponor Climate Controller C-46
Radiant emitter system
Solar tank
Solar panel
Diverting valve
Secondary circulation pump
34 UPONOR · FREE COOLING G UIDE

35. M
1
2
3
1
2
3
Free cooling with Uponor EPG6
The system diagram illustrates a Uponor free cooling
installation using a ground collector and Uponor EPG6
as a stand-alone system.
The EPG6 (3) is connected to a Uponor ground
collector (1) on the primary side of the free cooling
installation using the same supply line as to the heat
pump. If more than one ground loop is installed, a
manifold can be used to connect the ground loops.
The secondary side of the EPG6 is connected to the
heating pipe system before the manifold of the radiant
system (4).
Please note that a circulation pump (180 mm) has to be
added to the EPG6 in order to circulate the secondary
circuit. There is a blind piece on the EPG6 that can be
replaced with a pump.
The activation of the EPG6 cooling module can be
done automatically through the Uponor Climate
Controller C-46 included in the EPG6 or through
another external signal through the climate controller.
Ground collector (or bore hole)
Uponor EPG6 with Uponor Climate Controller C-46
Radiant emitter system
35UPO NO R · FREE COOLING GUIDE

36. Operation mode of Uponor
Climate Controller C-46
Two possible operation modes for cooling are described
below. The most typical operation mode of Uponor
Climate Controller C-46 is heating and cooling mode
when the controlled radiant system is used for both
heating and cooling emitter. In the case where a radiant
ceiling or wall system is installed purely for cooling
purposes, the operation mode is set to cooling mode.
This could apply to an example where cooling is needed
in an energy renovated house with radiators.
Operation mode heating and cooling of
Uponor Climate Controller C-46
When having a combined heating and cooling system
where you change between heating and cooling, the
climate controller always have to be in heating and
cooling mode, even though the climate controller is not
used as the primary controller for heating.
Uponor > Main menu > Control settings > Advanced control > Operation
mode. Note that the startup wizard will start when changing mode.
Heating min./max. supply Uponor
Climate Controller C-46
In the case of combined heating and cooling system,
where you can change between heating and cooling,
the climate controller C-46 must always be set to
Heating and cooling mode, even when the climate
controller is not used as primary controller for heating.
In this case the heating setting in the climate controller
must be neutralized as follows:
Uponor > Main menu > Control settings > Heating > Min./max supply
OK, also covered in startup wizard.
Operation of Uponor Climate
Controller C-46
Uponor EPG6 is delivered integrated with Uponor
Climate Controller C-46. It is important that the settings
and parameters are programmed to fit the designed
system. A detailed user manual describes all settings
and parameters.
Wizard – great installation guide
When Uponor Climate Controller C-46 is started for
the very first time, it guides the installer to make the
necessary primary settings of the system. Wizard helps
you step by step through the installation process. On
the display, the installer can read all about the set-up
and what to do next. The installation wizard is also
started after changing or resetting the operation mode.
Quick menu – gives easy access to basic settings
Made for end-users: The quick menu consists of a series
of screens easily accessible from the Uponor screen.
These screens display readings for daily use. If the
Uponor Climate Controller C-46 is set to installer access
level, it is also possible to modify some parameters.
Main menu – all informations and settings on the
whole
The main menu and all its sub-menus are used for
displaying any accessible information, parameter
settings, and selecting operating modes that are
accessible in the system.
Operating mode
Heating
Heating and cooling
Cooling
Min./max supply
Min
5.0 °C
Max
8.0 °C
36 UPONOR · FREE COOLING G UIDE

37. Uponor > Main menu > Control settings > Cooling > Dew point
The functions require Uponor Relative Humidity
Sensor H-56 and can handle up to six sensors, placed
in different rooms/zones. The sensor mode function
allows to decide which value to use in the dew point
calculation. It can be set as an average or maximum
value of the sensor. For cooling application, it is always
recommended to use the maximum sensor mode.
Uponor > Main menu > Control settings > Cooling > Sensor mode
Resulting supply water temperatures
The dew point control is activated if the cooling supply
setpoint is below the calculated dew point. The function
overrules the cooling supply setpoint, and automatically
adapts the temperature according to calculated dew
point based on the measured room temperature and
humidity of the room/zone. The resulting supply water
temperature is the calculated dew point + the dew point
margin.
Uponor Climate Controller C-46 calculates the dew
point using data from Uponor Relative Humidity Sensor
H-56, i.e. relative humidity and temperature. It is
displayed in the quick menu.
Cooling mode only
If the system works as a stand alone cooling system
without any change over between heating and cooling,
cooling mode is chosen:
Uponor > Main menu > Control settings > Advanced control > Operation
mode. Note that the startup wizard will start when changing mode.
Dew point management
parameters and settings
In the operation mode cooling, indoor compensated
supply with dew point control will help you to prevent
condensation problems if the actual condition in the
room/zone is different from the design criteria.
The supply water set point is referring to the design
supply temperature of the system, and is the absolute
minimum temperature that the Uponor Climate
Controller C-46 will provide. The supply temperature
should be set according to the design of the emitter
system, taking into account the limitations factors, such
as surface temperature and dew point.
Uponor > Main menu > Control settings > Cooling
The function also allows using a dew point margin as
an extra safety to compensate for having the variation
in room conditions, occupation of the room, etc. The
dew point margin can be adapted to the installation.
A smaller margin will improve the cooling power, while
a larger margin will reduce the risk of condensation.
The installation needs to be checked after startup and
re-configuration. If condensation occurs, the dew point
margin must be increased.
Sensor mode
Average
Maximum
Calculated dew point
18.3 °C
Dew point margin
1
Operating mode
Heating
Heating and cooling
Cooling
Supply setpoint
14.0 °C
37UPO NO R · FREE COOLING GUIDE

38. Uponor > Main menu > Control settings > H/C switchover > Bus master
Uponor > Main menu > General settings > General purpose output >
Mode
Heating and cooling change-
over: Uponor Climate Controller
C-46
Change-over between heating and cooling can also
be handled by Uponor Climate Controller C-46, either
automatically using the indoor-outdoor temperature
controlled switch-over, or a manual command. When
the change over from the climate controller is activated,
the hydraulic change-over with the diverting valve is
managed by the general purpose output (11 and 12)
that sends out a potential free signal. At the same time,
the same signal can be used through a relay to send a
signal to the heat source. The automatic change-over
indoor, outdoor and trigger parameters have to be
selected in the climate controller, as well as the function
of the general purpose output.
The heat source must be able to receive potential free signal, i e sense a
dry contact closure. The supplier of the heat source will be able to give
guidelines of which signal is available
Heating and cooling change-
over: external signal
When having a combined emitter system for heating
and cooling, the change-over between heating and
cooling system can be managed by Uponor Climate
Controller C-46 or through it. The climate controller
has several options for how to switch between heating
and cooling. The most common is to use the general
purpose input (5 and 6) in the climate controller, to
control that the system should switch from heating to
cooling. The general propose input is a contact sensing
input that can be connected to a relay in the heat
source or a manual switch. The heating and cooling
change-over behavior needs to be configured in Uponor
Climate Controller C-46. The hydraulic change-over with
the diverting valve is managed by the general purpose
output (11 and 12) that sends out a free signal using a
dry contact output.
Contact closing output from the best source or from manual switch. The
supplier of the heat source will be able to give guidelines of which signal
is available.
Activating the general purpose output needs to be
configured in Uponor Climate Controller C-46.
Uponor > Main menu > Control settings > H/C switchover
H/C switchover
Bus master
Bus slave
No bus
Bus master
Indoor and outdoor
Supply water temp.
General purpose input
General purpose output
Inactive
H+C commands
Fault signalling
V ~ 50 Hz
N L
0-10V
-
N
L
+
230 V ~
50 Hz
μ 2 A
230 V ~
G H I J K L
230 V
μ 2A
24VAC/DC
1 2 3 4 5 6 7 8 9 10 11 12
5 6
C-56
Reset
24 V
230 V
1
2
3
4
5
1
2
3
4
5
Heat pump
Pump
Diverting valve
Actuator 24 V
Relay (e.g. Uponor 1000517)
1
2
3
4
5
V ~ 50 Hz
N L
0-10V
-
N
L
+
230 V ~
50 Hz
μ 2 A
230 V ~
G H I J K L
230 V
μ 2A
24VAC/DC
1 2 3 4 5 6 7 8 9 10 11 12
5 6
C-56
Reset
24 V
1
23
4
5
Heat pump
Pump
Diverting valve
Actuator 24 V
Relay (e.g. Uponor 1000517)
38 UPONOR · FREE COOLING G UIDE

39. Uponor > Main menu > Control settings > H/C switchover
Uponor > Main menu > Control settings > H/C switchover > Bus master
Uponor > Main menu > General settings > General purpose output >
Mode
Pump management EPG6
The EPG6 is equipped with a Grundfoss circulation
pump Alpha 2L 25-60 for circulation of the primary
brine circuit. The pump is powered up through the
Uponor Climate Controller C-46 and prepared for pump
management. The actuator for the three-way mixing
valve is also powered by the climate controller and
connected to the control signal. The signal adjusts the
valve and secures the correct supply temperature using
the supply sensor which is also pre-installed in the
EPG 6.
In order to get the correct operation of the mixing
valve, motorised valves have to be selected in Uponor
Climate Controller C-46. The pump management also
has to be selected in the climate controller and in order
to get optimal control, “bus control” is selected. The bus
control will react on the secondary control system and
the pump will stop if there is no demand to the zones.
The secondary pump can also be connected through
the Uponor Climate Controller C-46, but the pump relay
has a limit of 100 W for the primary and the secondary
pump. The primary pump has a maximum consumption
of 45 W. Hence, 55 W is left for the secondary pump.
An alternative is to connect the secondary pump to the
secondary controller, i.e. Uponor Controller C-56.
Uponor > Main menu > Control settings > Advanced control > Pump
management
Pump management
Internal control
Bus control
Always on
230 V
μ 2A
24VAC/DC
1 2 3 4 5 6 7 8 9 10 11 12
C-56
Reset
DEM
65
Bus master
Indoor and outdoor
Supply water temp.
General purpose input
General purpose output
Inactive
H+C commands
Fault signalling
H/C switchover
Bus master
Bus slave
No bus
39UPO NO R · FREE COOLING GUIDE

40. 2012-12-18_UKProduction:UponorAB,IC/EL,Virsbo;Sweden
Uponor Corporation
www.uponor.com
Uponor reserves the right to make changes, without prior notification, to the specification of
incorporated components in line with its policy of continuous improvement and development.