The Putney School Field House

“This is not just a gym…We want this to be a place where our students can learn about being environmentally responsible, so that later in life, when they are making choices, they can say, ‘It’s possible. Our gym at school did it this way’.” – Randy Smith, Putney School

The design process for the Putney School Field House started from the client’s request, to design the highest quality environmental building within their budget. The team modeled and evaluated a range of energy and environmental building alternatives, comparing construction costs, 30-year operating costs and CO2 emission.

Some options were removed from consideration almost immediately because they did not go far enough in reaching the School’s sustainability goals. The net-zero option gained final approval from the school. From the School’s perspective it seemed much easier to raise the extra money needed for the construction of a model building than for an endowment for ongoing operating costs for a less-efficient building. The School also decided to seek platinum LEED certification for the project to confirm their efforts with third-party verification.

Throughout the design process, Maclay Architects, working with the design team, conducted multiple day-long work sessions with students, faculty and staff, focusing on key design points. While these sessions added time, voices and viewpoints to the design process, they allowed for a building that speaks of and to the school community. Upon completion, educational signage was placed throughout the building to explain the unique building features and enhance the experience of visitors through learning.

Super-insulation and extensive air sealing were integral to reducing the energy consumption of the facility. To reduce heating energy use by 77% compared to the ASHRAE Standard 90.1-2007 baseline building (Appendix G), the following high insulative levels were used: R-60 roof, R-45 walls above grade, R-20 slabs, R-20 foundation walls below grade and R-5 windows. Through careful design and execution the building achieved a tested air leakage rate of 0.065 cfm/sq ft. of above ground building shell at 50 pascals test pressure or 1,625cfm-50 total air leakage rate. 

Consideration of mechanical systems included both ground-source and air-source heat pumps. Though the air-source system was less efficient than the ground-source system, the solar panels required to cover this inefficiency required less investment than the difference of cost the systems. Based on the cost and the simplicity of the system, the school chose to install the air-source system. To achieve the zero energy goal an investment in renewable on site renewable energy systems included 36.8 kW of solar tracking collectors installed to the north of the Field House.

Construction on the Putney School Field House began in 2007 and was completed in October 2009. The 16,800 square foot Field House is New England’s first net-zero athletic building and received LEED Platinum certification from the U.S. Green Building Council.

Quick Facts


418 Houghton Brook Rd.
Putney, VT05346
United States
Building Type Athletic Facility and Gathering Space
Project Type
Basis of Performance Claim
Conditioned Floor Area 16 814

Energy Summary

Energy Data Type
Renewable Energy System Type(s)
Annual renewable energy generated

Envelope and Mechanicals

Subslab assembly

4” EPS under whole slab

Foundation wall assembly

2” EPS panel to 48” depth

Above grade wall assembly

gym wall: 17” of cellulose insulation, all other spaces: 8” of cellulose and 2” of Poly-isocyanurate

Door Assembly
Air Changes per hour, ACH50

Project Team:

Other Team Members:




Completion Date:


Type of Construction
Number of buildings
Floor area of each building
Conditioned Building Volume
Conditioned Floor Area 16 814

Location and Climate Details

Athletic Facility and Gathering Space

418 Houghton Brook Rd.
Putney, VT05346
United States
Location Type
Climate Region Zone 6
Köppen Climate Type Dfb
Lat. / Long. POINT (-72.553954 42.9874719)
Elevation 920
Solar Insolation 4.45 kWh/m2/day
Annual CDD and Base Temp |
Annual HDD and Base Temp |


Site Conditions:

Site Description:

Monthly Energy Data and Utilities

Energy Data Type:

Electric Utility: Green Mountain Power

Gas Utility:

Renewables and Energy Balance

Renewable Energy Sources:

Renewable Energy System Description & Details:

Annual renewable energy generated
Annual Renewable Energy Generated Data Type
Power Rating 37Watts
Renewable Energy System Type(s)
Source of Annual Production Data

Walls and Roof

Subslab assembly

4” EPS under whole slab

Subslab R-value 20.00
Slab edge assembly

3” EPS at slab joint

Slab edge R-value 15.00
Foundation wall assembly

2” EPS panel to 48” depth

Foundation wall R-value 10.00
Above grade wall assembly

gym wall: 17” of cellulose insulation, all other spaces: 8” of cellulose and 2” of Poly-isocyanurate

Above grade wall R-value 45.00
Cathedral ceiling assembly
Cathedral ceiling R-value

Windows and Doors

Window Assembly:

a. Triple-glazed, low-e, argon filled: U-value – 0.15, SHGC – 0.28, VT – 0.49
b. Skylights in wellness spaces and offices (Velux), double-glazed, low-e, argon filled: U-value – 0.4, SHGC – 0.34, VT – 0.54
c. Skylights in gymnasium (Sun Optics), triple-glazed, prismatic acrylic: U-value – 0.35, SHGC – 0.74, VT – 0.66

Door Assembly:

Average window U-factor 0.15
Door U-Factor
Door Area

Mechanical Systems

Space cooling - Manufacturer & Model Daikin Multi-City VRV air source heat pumps,
Space heating - Manufacturer & Model Daikin Multi-City VRV air source heat pumps,
Domestic hot water - Manufacturer & Model Lavatory water heater, 0.75 GPM instantaneous, 100°F, EX65TFS-100°, Heat pump water heater, E-Tech R060 80 gal electric water heater
Domestic hot water - capacity
Ventilation - Manufacturer & Model
Lighting Manufacturer and Model
Lighting Efficiency
Mechanical Equipment Installation Details and Comments


Air Changes per hour, ACH50
Air Changes per hour, CFM50

General Process

Design for Adaptability:

Software Tools

Software Tools:

General modeling information:

Lessons Learned

Outcome of Project Goals:


Rebates and Financial Incentives

Federal incentives
Local incentives
State incentives
Utility incentives
Other incentives