Grayslake, IL - Prairie Crossing Four Square - Case Study

Grayslake, IL

Project Team: Building Science Corporation, Prairie Holdings Corporation

Address: Grayslake, IL

Description: 2,650 ft2 four bedroom, 21/2 bath house with an optional fireplace and fully insulated basement and attic living space with optional bath and dormers

Every home built by Prairie Holdings Corporation has a controlled ventilation system that enhances indoor air quality and comfort by bringing in outside air when needed by the occupants. Typical homes have no way of providing outdoor air in a controlled manner aside from relying on the construction of leaky homes and the whims of the weather (wind and temperature differences). Leaky homes consume energy and tend to be uncomfortable from drafts. Tight homes without controlled ventilation can also have problems due to a build up of odors and other pollutants. The optimum approach for healthy, safe, comfortable, energy efficient homes is to construct a tight building envelope and provide controlled mechanical ventilation.

Building Envelope

An advanced framing system using 2x6s on 24-inch centers, single top plates and stacked framing allow for more insulation in a thicker wall and reduces thermal bridging. Exterior rigid foam sheathing with taped joints acts an exterior air barrier as well as a drainage plane eliminating the need for building paper or housewrap.

First floor plan
(above left); second floor plan (above right)


Low-emissivity, argon-filled windows increase the insulating value over standard windows.

Mechanical Systems

A sealed combustion condensing gas furnace is completely isolated from the inside air. Combustion air is drawn from the outside with a minimal chance of combustion products spilling into the conditioned space. The water heater is a power vented model. A programmable setback thermostat with a timer is installed which reduces the energy demand. The tighter building envelope, the high-performance
windows and the increased levels of thermal insulation allow a considerable simplification and reduction in size of the duct distribution system for heating and cooling. Moving the ducts within the conditioned space eliminates duct leakage to the exterior as well as limits
the temperature difference at the ducts. These improvements result in reduced heating and cooling loads which allow the air conditioning unit to be downsized as well.

Controlled mechanical ventilation is provided by a fresh air supply-only system with an AirCylcer for mixing.