Heat and Moisture in the Atmosphere and Human Comfort
1.
2. is the amount of energy flowing from one body
to another due to their temperature difference,
or by any means other than through work.
3. Your own body is the main source of heat. Three-fourths of the energy
you convert for physical work turns into heat, only one-fourth into
motion. When your body is active, it usually generates more heat than it
needs and therefore has to release some.
4. The harder you work, the faster you generate heat, and the more your
body has to get rid of heat. Hot weather and high humidity increase your
risks by slowing the transfer of heat to the air around you.
When you produce heat that raises internal temperature, your heart rate
increases and vessels expand to bring more blood to the outer layers of
skin, where the heat is released.
If excess heat is not released fast enough this way or the surrounding air
is warmer than your body, your sweat glands go to work. They draw
water from the bloodstream to make sweat that carries heat through
pores and onto the skin surface, where it evaporates and releases the
heat.
5. Once the air reaches
saturation (The level at
which it cant absorb any
more water in gas state,
a.k.a humidity) water will
condense as drops in the air
causing clouds/mist/fog,
which is moisture.
6. Human comfort is achieved when the environment
provides the appropriate conditions to avoid
feeling too cold or hot.
7. The six factors affecting thermal comfort are
both environmental and personal. These
factors may be independent of each other, but
together contribute to an employee’s thermal
comfort.
8. THE SIX BASIC FACTORS
Environmental factors:
1. Air temperature
2. Radiant temperature
3. Air velocity
4. Relative Humidity
1. Clothing Insulation
2. Metabolic rate
11. RADIANT
TEMPERATURE
The weighted average of all the temperatures from
surfaces surrounding an occupant.
Examples of radiant heat sources include: the sun,
fire, electric fires, ovens, kiln walls, cookers, dryers, hot
surfaces and machinery, molten metals etc.
12. AIR VELOCITY
This describes the speed of air moving across the
employee and may help cool them if the air is cooler than
the environment.
Air velocity is an important factor in thermal comfort
for example:
Physical activity also increases air movement, so air
velocity may be corrected to account for a person's level of
physical activity
13. RELATIVE
HUMIDITY
If water is heated and it evaporates to the surrounding
environment, the resulting amount of water in the air will
provide humidity.
High humidity environments have a lot of vapour in the air,
which prevents the evaporation of sweat from the skin. In hot
environments, humidity is important because less sweat
evaporates when humidity is high. The evaporation of sweat is
the main method of heat reduction.
14.
15. CLOTHING
INSULATION
Thermal comfort is very much dependent on the insulating
effect of clothing on the wearer.
Clothing is both a potential cause of thermal discomfort as
well as a control for it as we adapt to the climate in which we
work. You may add layers of clothing if you feel cold, or
remove layers of clothing if you feel warm.
16. WORK RATE/
METABOLIC HEAT
The more physical work we do, the more heat we produce. The
more heat we produce, the more heat needs to be lost so we don’t
overheat. The impact of metabolic rate on thermal comfort is critical.
A person’s physical characteristics should always be borne in mind
when considering their thermal comfort, as factors such as their size
and weight, age, fitness level and sex can all have an impact on
how they feel, even if other factors such as air temperature,
humidity and air velocity are all constant.
18. Buildings are designed for people,
and those people are trying to
accomplish a task – whether it’s
raising a family, running an office,
or manufacturing a product. The
building needs to keep people
comfortable, efficient, healthy, and
safe as they set about their task.
19. THERMAL COMFORT
Maintaining a person’s thermal comfort means ensuring that they don’t feel too
hot or too cold. This means keeping the temperature, humidity, airflow and
radiant sources within acceptable range.
20. Metrics
To keep people comfortable you need to provide the
right mixture of temperature, humidity, radiant
temperature and air speed. The right level of these
variables depends on what activity is occurring, how
active the people are, and what they are wearing.
21. Design Strategies
Some ways to keep people comfortable are to use the
sun’s heat to warm them, use the wind or ceiling fans to
move air when it’s too warm, and keeping surrounding
surfaces the correct temperature with good insulation.
HVAC equipment like boilers, fans, and heat exchangers
can temper the air temperature and humidity, but
surface temperatures and moving air have to be
considered too.
22. VISUAL COMFORT
Maintaining visual comfort means ensuring that people have
enough light for their activities, the light has the right quality and
balance, and people have good views.
23. Metrics
Good lighting is well-distributed, is not too dim or too
strong, and uses minimal energy. Lighting is often
measured either by the amount of light falling on a surface
or the amount of light reflecting off of a surface. Good
visual comfort also generally means that as much of this
light is natural light as possible. Humans are hard-wired to
like the sun’s light and it saves energy.
24. Design Strategies
Daylighting design strategies like high windows, light
shelves, and well-placed skylights can help distribute
sunlight inside a space. When you do need to use artificial
lights, you can reduce energy use by using efficient
fluorescents or LEDs, with daylighting dimming controls,
effective fixtures, and good lighting design. Good controls
can automatically balance natural and artificial lighting.
25. AIR QUALITY
In addition to air that’s the right temperature and humidity for
thermal comfort, it’s important that air is clean, fresh, and
circulated effectively in the space
26. Metrics
Fresh air requires a certain percentage of outside air
circulating into spaces. Clean air requires pollutant and
pathogen levels to be below certain thresholds.
27. Design Strategies
Air can be kept fresh with high ventilation rates, either
using natural ventilation such as operable windows and
skylights, or active systems such as HVAC fans and
ducts. Clean air can be achieved by filtering air, by
flushing spaces with fresh outside air, and by not
contaminating the air with impurities from the building,
such as volatile organic compounds from paints or
materials.
29. Metrics
How humans perceive sounds and loudness is a
subjective measure. However, you can create a
comfortable environment by controlling objective measures
like decibel level (sound pressure), reverberation time, and
the sound reflection and damping properties of materials.
30. Design Strategies
Creating barriers and sound breaks between sources of
noise is important. You can optimize room shape and size
to reduce echoes and reverberation. And you can use
acoustic tiles on ceilings and walls to dampen the sound.
Transfer of energy from one body or surface to another
When you receive or gain heat, you also need to release heat
Pag naabot na nung air yung level kung saan hindi na nito kayang magabsorb ng mas maraming tubig, magcocondense ung tubig habang bumababa sa hangin na magko-cause ng clouds, mist, fog o moisture kung tatawagin natin
Temperature sa paligid
Average ng lahat ng temperature sa paligid
Bilis ng hangin na nakakaapekto rin sa katawan ng tao.
Why it's important?
Creating comfortable conditions is one of the biggest uses of energy in buildings and it is also critical to the happiness and productivity of its users. Often factors such as airflow and radiant temperature are overlooked in a design, leading to higher energy use and occupancy dissatisfaction.
HVAC
HEATING, VENTILATION AND AIR CONDITIONING
Why it’s important?
Good lighting helps create a happy and productive environment. Natural light does this much better than electric lighting. Having good views and sight-lines gives people a sense of control of their environment and provides a sense of well-being.
Why it’s important?
If air is too stale or is polluted, it can make people uncomfortable, unproductive, unhappy, and sick. Fresh air helps people be alert, productive, healthy, and happy.
Why it’s important?
People are more productive and happy when they’re not distracted by noises from outside or from surrounding spaces and occupants. Acoustic comfort is especially important for schools and office buildings.
