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NetZero Energy Architects "Hybrid" Home Energy Design

Solutions that Reduce Home Energy Use While Increasing Quality and Comfort.
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Crawl Space
Passive Geo-Exchange Crawl Space Conversions


Crawl Space Energy

“Capturing Geo-ThermalEnergy in the crawl space”

Due to the energy concerns of today, people are sealing their homes tightly to save energy on heating and air conditioning. Unfortunately, these tightly sealed homes are developing very unhealthy indoor air quality. Consequently, a new mechanical code is being adopted as of January of 2011 that will require fresh air changes in new residences to combat this unhealthy indoor air quality. In conjunction to this, a new energy code also requires new furnaces to have a “constant fan” feature, which saves heating and cooling energy by mixing the indoor air of the home. This clean air requirement and the necessity to circulate air within the homes have opened up an opportunity to provide fresh air and cut energy consumption using an ERV and an encapsulated crawl space.

An “Energy Recovery Ventilator” (ERV), can provide fresh air with minimal loss of indoor temperature. This simple device is cost effective, uses little energy, and transfers the energy of the incoming “clean air”, to the exiting “stale air”, maintaining the temperature within the home.

Have you ever noticed that the temperature in a basement is warmer in the winter and cooler in the summer? This is because the earth’s temperature is a constant 55- 57 degrees Fahrenheit. We can utilize and benefit the home’s heating and cooling needs, by capturing this energy source. This can be accomplished by a passive nearly maintenance free way, when used in conjunction with the new ventilation needs of our homes. A mechanically ventilated crawl space will become part of a “Hybrid” geo-exchange system, by encapsulating the crawl space; therefore it will assist the heating and cooling needs of the home. Traditional crawl spaces which are vented to the exterior, for the prevention health reasons of mold and decay, increase the home’s energy loss. This old ventilation code was adopted several decades ago, long before the energy concerns of today.

“Air Flow Design”, or ventilation and distribution, is a key component in the overall energy efficiency of our homes thermal and health needs, and can become an opportunity for a cost effective way to capture and utilize the ever-present abundance of “Geo-Thermal” energy.

James Phillip Wright AIA

Energy Architect


Adam Shane and James

Energy Recovery Ventilator(ERV)

The Earth’s ambient / passive geo-exchange energy contribution of a home with the crawl space sealed off from the exterior. The idea behind Geo-exchange / crawl space is similar to Geo-thermal energy with the earth.

  • Reduce utility bills

  • Cleaner and healthier air quality for your home

  • Less impact on the environment


Earth’s ambient / passive geo-exchange energy contribution,

In the winter

The sealed up crawl space blocks cold air from entering the home envelope thus cooling down your house from the underside. It will absorb radiantly from the earth keeping your house warmer, saving you energy and therefore money for heat.

In the summer

The sealed up crawl space blocks out the hot exterior air and utilizes the cool ground for radiant loss to the earth to keep your home naturally chilled.

In addition, energy will be saved, because of the reduction of building envelope heat gain / loss, which is equivalent to the area of the home’s foot print.

The Passive SystemThe least expensive

  • Seal Up exterior vents

  • The crawl space has been encapsulated.

  • Mechanically ventilation to be provided with an air to air heat exchanger called an Energy Recovery Ventilator (ERV) transfer is typically 75-90%

  • Studies show 15-25% utility bill savings, depending upon environmental factors

The Hybrid systemThe most efficient system

When combined with the homes mechanical HVAC system, proper insulated, you will create an energy source of passive / geo-exchange.

  • Air tightness of the cavity being used as an air return / plenum per code. The crawl space has been encapsulated from moisture and air infiltration, meeting code requirement of an approved continuous vapor retarder for mechanically ventilated crawl spaces.

  • Insulate at the rim / floor joist, and the seams of the wall framing above the concrete foundation

  • Alteration of the mechanical return ducting system. In some cases this only requires minimal work.