dbHMS designed project Hybrid House was the winner of ASHRAE’s Regional Technology Awards program. The awards are given to projects in 7 different categories at the region level.

The Hybrid House is a 2,100 square feet two-bedroom single family home located on the south side of Chicago. The homeowner also, a structural engineer wanted to build a green sustainable home at an affordable cost. The home is a “hybrid” between a net zero energy house and a typical market home. Several months of extensive energy modeling went into the design of the project to evaluate several passive and system options. The predicted utility bills for the home are $316 for the entire year and data collected so far over the course of the year has reflected better than predicted performance in spite of a sharp increase in utility costs in the market. Last year’s utility data indicates a total utility bill of $135 for the year.

The home has an office, living room, dining room, kitchen, half bathroom, storage and mechanical spaces on the first floor. The second floor contains a master bedroom and bathroom, a second bedroom, family room, storage and a second bathroom. The first floor also includes a mass floor for passive heating. Sheet metal forms with concrete over them form a return air path and provide thermal mass. Optimized overhangs shade the fenestration from the high summer sun while insulated interior shutters help hold the passive heat inside the home on cold nights.

The building envelope for the Hybrid House is comprised of super insulated opaque assemblies and high performance fenestration. Walls are R35 while the roof is R40 overall insulation. Low-E windows with a U-value of 0.29 and a shading coefficient of 0.27 are incorporated in to the home.

The home uses compact fluorescent lighting for illumination resulting in low lighting power densities. High efficiency appliances further add to load reduction in the home.

The building systems include a water to air geo-exchange heat pump which provides heating and cooling. The heat pump is supplemented by a solar thermal hot water system, which also provides domestic hot water to the home. The home includes a passive natural ventilation system assisted by two 15-inch turbine ventilators.  A 4.8 kW photovoltaic array on the roof (angled to maximize the output of the array) generates electricity for the home.

Energy Efficiency

A comparison of the home’s energy use with the US Department of Energy’s Information Administration published data for homes in the Midwest indicates the following:

Innovations
The passive measure implemented in the home result in a heating system which is 25 percent of the size of a system for a typical home while the cooling system is 60 percent of the size of a system for a typical home.  Apart from the several building system innovations described above, the home also incorporates a gravity storm water harvesting system which the owner utilizes to water the organic garden. The short driveway for the garage is paved with pervious concrete to reduce water runoff. The home is an excellent example of creative design to accomplish big goals and utilizes technologies in a unique combination from the past. It is an affordable alternate at building energy efficient homes.

Environmental Impact

The reduction in energy use and the generation of energy by this home is enough to reduce the green house gas emissions from 1.4 homes!  This equates to about 10.2 metric tons of carbon dioxide in a year (EPA Calculator)

In summary, the home design and construction are a result of good integrated design process to build a home of the future within a reasonable budget and time line.