Concord 4 Square Retrofit

The Concord 4-square project is a research study in methods and materials for Deep Energy Retrofits which Synergy completed in conjunction with Building Science Corporation and their chief building scientists.  Very early in this new wave of retrofits, new theories were put into practice to answer the question, can a 50% reduction in energy usage be met with existing housing.  We far surpassed this modest goal, and laid the ground work for the most popular form of Deep Energy Retrofit, exterior application of rigid foam.

The project met a 65% energy reduction with envelope and HVAC upgrades.  The home owner has since gone further to a Zero Energy home with the addition of 5.0 kw Solar PV array.

THE PROJECT SUMMARY FROM THE BUILDING SCIENCE CORPORATION WEBSITE:

The Concord Project:  Summary Results
Description: 3,600 ft² two-story, 4 bedrooms, 3¹/₂ bath single family home
Completion Date: October 2008
Annual Utility Costs:

• Gas before retrofit: $2,400/year
• Gas after retrofit: $858/year
• Electric before retrofit: $960/year
• Electric after retrofit: $471/year

Total Annual Utility Savings: $2,031/year

The Concord Project:  Building Enclosure
Roof: Unvented
Attic Insulation: R-60 with 4” rigid foam on the exterior and 5” high density sprayed polyurethane foam to the underside of the roof sheathing
Roof insulation: Two layers of 2” polyisocyanurate rigid insulation

Air Sealing: Airtight drywall approach; low expanding foam sealant around windows, sealants and adhesives used between framing components
Window Specifications: Double-glazed, Low-E, argon-filled: U=0.33
Wall Insulation: R-41 with blown cellulose cavity insulation and 4” of rigid foam on the exterior

Foundation: Conditioned basement
Foundation Wall Insulation: R-20 walls with 4” high density sprayed polyurethane foam
Slab Insulation: R-10; 2” XPS insulating sheathing under the slab

Drainage Plane: Taped foil-faced polyisocyanurate
Radon Protection: Passive system installed
Infiltration: 2.5 in² leakage area per 100 ft² envelope

The Concord Project:  The Mechanical Design
Heating: 92% AFUE sealed combustion gas boiler in conditioned space
Cooling: 13 SEER split system in conditioned space
Ventilation: Supply-only system with outside air to return; run at low speed with an ECM motor
DHW: 0.8 EF side-arm storage tank
Appliances: ENERGY STAR dishwasher, refrigerator, range, clothes washer, clothes dryer
Lighting: Energy Star CFLs
Site Generated Power: None (Now upgraded with 5.0 KW Solar Array)