The Coastal Maine Botanical Gardens wanted to construct a new educational center adjacent to their existing visitor’s center to house both administrative office space as well as flexible and adaptable classroom space that could also be used for various events and gatherings. The building needed to establish a strong connection to the outdoors and the neighboring botanical gardens. The client also set out strict environmental guidelines from the beginning of the project, requiring the building to have minimal energy loads and be both LEED Platinum certified and net-zero. Many high-performance building strategies were incorporated into the design in order to achieve the net-zero goal. The building’s super-insulated envelope features R-20 below ground insulation, R-40 above ground walls, an R-60 roof and R-5.5 windows. A panelized wall system constructed off-site reduced waste and minimized site disturbance. On site 90% of construction waste was recycled. Locally harvested, FSC certified wood was used extensively. The building is sited to take advantage of ample southern light. Natural daylighting, along with energy efficient fixtures reduce lighting loads by 60%. Rainwater collection and high-efficiency fixtures reduce water demand by 75%. Operable windows open to provide natural cooling and ventilation. A variable volume refrigerant heat pump system provides both heating and cooling. This air-to-air heat pump extracts heat from the outside air in the winter and rejects heat to the outdoors in the summer. Energy recovery ventilators provide fresh air while recovering about 70% of the heat from exhaust air. A solar domestic hot water system reduces energy demand, while a 45 kW rooftop mounted photovoltaic system provides clean, on-site energy. The building is intended to be a teaching tool for visitors to communicate the importance of resource and energy conservation. Meters on display in the building provide real-time data for indoor and outdoor lighting, water use, electricity production and mechanical systems.

1. Coastal Maine Botanical Gardens
Net-Zero Project Example
Photo
by
Robert
Benson

2. STEP 1
Collaborative,
Integrated Design
Methodology

3. STEP 2
Immersion in the
Soup of the
Universe

4. STEP 3
Create your
Vision / Imagine
your Future
• Site Options
• Aesthetic Options
• Construction Options

5. STEP 4
Making your Vision
Real
• R-40 Walls, R-60 Roof, R-5 Windows
• 10-20 kBtus

6. STEP 5
Empower your
Team
This
is
where
project
team
goes

7. STEP 6
Design Projects
like a Living
System

8. STEP 6
Design Projects
like a Living
System

9. STEP 6
Design Projects
like a Living
System

10. STEP 7
Minimize Loads
• Insulated Envelope
• Maximize Daylighting
• Reduce Cooling
• Occupancy Controls

11. STEP 8
Optimize
Mechanical
Systems
• Air Source Heat Pumps
• Energy Recovery Units
• Minimal Distribution
• Rainwater Use

12. STEP 9
Power with
Renewables

13. STEP 10
Building

14. STEP 10
Building

15. STEP 10
Building

16. STEP 10
Building

17. STEP 11
Operation for
Success

30. STEP 12
Celebration,
Learning &
Evaluation
Educating

31. Path to a Net-Zero Mad River Valley
1. Calculate existing loads
2. Estimate load reduction
3. Estimate renewables needed to meet load
4. Evaluate changing infrastructure for further reduction
TOTAL ENERGY LOAD:
166,000,000 – 476, 000,000 kWh
or 567,000,000 – 1,625,000,000 kBtus
With energy conservation we can realistically expect
to reduce energy loads by around 25%.
We would then need:
132,000 barrels of oil
55,000 cords of wood, 55,000 acres of woodland
192,300 kW of installed PV, 1150 acres or 1.8 square miles
27 wind turbines (2.3 Mw with 100 meter blades)
assuming a wind speed of 7.5 mps, requiring ridgeline placement

32. A Net-Zero World
Bill Maclay, Design principal Maclay Architects
bill@maclayarchitects.com
Photo
by
Ayacop
/
CC
BY
2.5