Walls and Roof

During the schematic design phase, the team investigated several levels of thermal performance. Wall and roof system options were evaluated based on expected energy performance, initial construction cost and long-term operating costs. Three alternatives for wall construction were analyzed for performance and capital and operating costs.
• Leave the existing exterior brick in place and insulating from the inside by using spray foam behind the existing veneer.
• Demolish the existing exterior brick and insulate from the outside using rigid foam, plus installing a new metal panel rain screen.
• Demolish the existing, exterior brick and insulate from the outside using rigid foam, plus installing a new ventilated brick-veneer rain screen.
The design team investigated each of these wall options with multiple levels of insulation. Comparing the potential return on investment for each of the options, it was determined that the optimum value was achieved by demolishing the existing brick and installing 4” of polyisocyanurate board insulation under a combined brick-veneer and metal-panel rain screen wall assembly.

In addition to the high thermal performance achieved by the wall assembly, a combined air/moisture/vapor barrier was applied continuously over the entire building envelope. This spray-applied barrier combined with membrane layers, used at corners and non-adhesive surfaces, was specifically detailed to ensure that the resulting building would be one of the tightest commercial buildings in Vermont. In final blower door testing the building reached a result of 0.11 cfm50/square foot exterior surface area, which put this building in the top 10 percent of buildings tested in Vermont.

Subslab assembly

Retrofit - 3" new EPS insulation
New - 4" EPS insulation

Subslab R-value 20.0
Slab edge assembly

4" EPS to 36" deep

Slab edge R-value 20.0
Above grade wall assembly

4" polyiso rigid insulation

Above grade wall R-value 27.0
Roof Assembly

Retrofit - 6" new polyiso and 4.5" existing polyiso
New - 9" polyiso

Roof R-value 54.0

Windows and Doors

Window Assembly:

Accurate Dorwin triple pane windows. Wasco skylights in the offices U 0.1, SHGC 0.54, VT 0.5

Average window U-factor 0.19
Solar Heat Gain Coefficient 0.34
Visible Light Transmittance 0.41

Mechanical Systems

Space heating - Manufacturer & Model Open-loop ground source shallow aquifer with plate and frame heat exchangers and console heat pumps.
Domestic hot water - Manufacturer & Model Solar Thermal ~60% of the load, propane for the remaining
Ventilation - Manufacturer & Model Thermotech enthalpy wheel -70% effective
Lighting Manufacturer and Model High-efficiency florescent and LED lamps throughout, open-loop daylight harvesting in all third-floor conference and courtrooms and north-facing offices, dual switching in all other rooms, Lutron GRAFIK Eye with EcoSystems.
Lighting Efficiency
Mechanical Equipment Installation Details and Comments

Full building mechanical commissioning by Cx Associates.