One-Watt-Houses are designed to use no more than One Watt per square foot in heat and eliminate the need for conventional heating systems. In addition, a One-Watt-House use no more than 10kWh (34kBtu) per square foot in primary energy. These targets are inspired by the German Passivhauses.

One-Watt-Houses reduce the total energy demand of a building by 60 - 80% relative to average Mid-West buildings. To help understand these values, 20 x 100Watt light bulbs supply enough heat for a 2,000 sq .ft. home during the coldest day of the year. Consequently, most active heating and cooling equipment can be eliminated.

One-Watt-Houses are heated and cooled passively most times of the year. The necessary added heat during climate extremes can supplied with a variety of low load solutions. A fundamental design goal of One-Watt-Houses is simplicity:
The extra investment in insulation, windows and other passive house components is rewarded with savings in mechanical systems. Furnaces are not needed. Instead, we can use a on-demand water heater, heat pumps, solar thermal or other sources for both space heat and domestic hot water needs. CTI analyses available energy sources, heat load and the house system as a whole to determine the optimal HVAC solution for the building.

(Contact CTI for detailed questions on heating and cooling solutions in your location)

Energy Star is a broad initiative established by the Department of Energy to promote energy efficient appliances, devices and buildings. Any building which is 15% more efficient than the local reference building can achieve an Energy Star rating. One-Watt-Houses are 60 - 80% more efficient than average - raising the bar significantly.

LEED (Leadership in Energy and Environmental Design) is a growing standard for "green building" in the US within which Energy Efficiency is one of many aspects. It looks at the building process comprehensively and attempts to improve site selection, material choices, transportation, and other building attributes. One-Watt-House™ and LEED are complementary - in fact we can help LEED to be more effective. Other, non-energy criteria of LEED should be applied where possible. We do believe that energy efficiency takes priority, considering the related resource, climate and political challenges of this century.

Zero-Energy-Buildings supply enough renewable energy to neutralize the on-site demand of a building. If the building is not based on a very high level of energy efficiency, it will require major investments in renewable energy features. A One-Watt-House prioritizes first on energy efficiency investments to minimize energy load.  Starting with a super efficient, passive building will significantly lower the need for active systems.

Additional investments can go into super efficient refrigerators, cars, and other household items to further lower one's carbon foot print.

Plenty of envelope and wall solutions are available in the US: most common are light wood frame and loose fill insulation. Structured Insulated Panels (SIPs), a sandwich of OSB panels and foam insulation, offer a good alternative. Extra attention is needed when selecting windows, heat recovery ventilators, doors, and other components to complete the super insulated envelope. For example, a typical One-Watt-House window uses 3 panes of glass with an Ar or Kr gas and one or two coats of heat reflective coating (low E).

One-Watt-Houses typically achieve HERS® ratings between 30 and 42. (A newly built local reference building - build excactly to meet IBC 2004 - scores a HERS® 100)

HERS: Home Energy Rating System - a nationally reckongized system for rating homes. The system is also basis for determining Energy Star® and LEED® credits and is the only rating system endorsed by the IRS. A HERS 100 is an exactly average local reference building complying with the International Building Code 2006.

Please also refer to http://www.natresnet.org/

The maximum heat load describes how much heat is lost and must be supplied in a building at the time of climate extremes to insure indoor comfort. For Chicago, the design load is 0°F. Because a One-Watt-House™ loses its heat much slower in those extremes, temperature lows and peaks are less noticeable. Heat Load is a dynamic measure and expressed in Watts or Btu/hr .

Total on-site energy demand includes all fuels & forms of energy supplied: electricity, natural gas, propane, etc. typically over one year and is measured in kWh, Btu, Therm, per conditioned floor area etc.

Primary Energy (PE) is the amount of energy the power plant needs to process in order to balance the total on-site energy demand.  It includes inefficiencies during generation, distribution and transformation of energy.  The total Primary Energy of a building depends largely on the local power supply structure and the Primary Energy conversion factors. The national average Primary Energy conversion factor is about 3.