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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 Facts

Case Study # 1 & #2 are being updated

Case Study # 3

” Clean Air Crawl Space Energy”

San Carlos California

The “health” needs of the owner inspired the renovation of their 1930’s single story 1700 s.f. Californian Bungalow. These health issues wer the result of bad crawl space air quality caused by the presence of mold spores, fungus, decay, elevated radon levels, asbestos deterioration, termite, and other health concerns. These contaminants were infiltrating into the cavity of the occupied envelope of the home, from the crawl space, and were contributing to the health decline of our client. To solve the air quality issues, we had to seal up the building envelope and introduce “Mechanical Fresh air Ventilation”. We used a “Continuous Whole Building Ventilation” system, incorporating a heat recovery ventilator (HRV), which jointly harnesses the Earth’s natural thermal energy, in this damp, musty, temperate, crawl space.

The home retrofit consisted of encapsulating the crawl space, sealing of the existing HVAC plenum & ducting, andair sealing” the building shell. The result was an isolated and reasonably air tight living envelope. The HRV transfers the majority of the stale, indoor air temperature to the incoming fresh air, maintaining the temperature of the building.

Our solution established a positive air pressure in the occupied envelope, forcing shell contaminants to the exterior of the 80 year old framing. By sealing off of common envelope components, and creating a negative pressure management system within the crawl space, we prevent infiltration into the living envelope. This negative air pressure meets the intent of the ASHRAE Standard 62.2for “Ventilation and Acceptable Indoor Air Quality in Residential Buildings”.

By utility monitoring before and after this system, our goal, in addition to this system improving the air quality and health of the building’s occupants, is to make our integral heating and cooling system, a “passive / hybrid” / geo-exchange system, eligible for the geo-thermal 30% federal tax credit, by illustrating with data, how much this system can reduce the energy consumption of our homes.

James Phillip Wright AIA

Energy Architect

Case Study Home # 4

Evaporative Cooler / Geo-Exchange / Basement Energy

Edgewater, Maryland

Our renovation project is a two story 1500 s.f. home, with a 500 s.f. basement. The home has been gutted to the framing, and insulated with spray foam, and sealed as an air tight envelope, therefore requiring “Continuous Whole Building Ventilation”, for healthy indoor air quality.

The beauty of our energy exchange system is that it harnesses the “Geo Thermal Energy” of the earth, and natural cooling effect of evaporating moisture. We began with the need to convert a damp basement into a dry mold free space. The damp, musty, cool, un-waterproofed basement walls inspired our concept of harnessing the Earth’s natural & thermal energy to create Geo-Exchange cooling and heating. This transfer of geo-exchange energy is accomplished by surrounding a basement w/ a ventilated envelope, by means of an Energy Recovery Ventilator (ERV).

During the cooling season, the ERV extracts the moisture from the fresh incoming air and delivers dehumidified fresh air into the building envelope. Within the basement, we created a sealed air tight living envelope surrounded by an air cavity adjacent to the existing old subterranean walls. These leaky walls also “wick” moisture, as well as sweat condensation during the hot / humid summers, thereby creating a natural environment for an evaporative chiller. Our approach is to encourage the presence water, contrary to traditional thinking, and our system harnesses the evaporative cooling effect resulting from ventilating a cavity with “drystale air”.The aforementioned, will result in dramatic cooling at minimal energy use of approximately +/- 150/watts of electricity / hour.

When in the heating season, we incorporate an additional HRV unit ventilating the basement cavity producing “Geo” pre-conditioned fresh air entering the main house ERV.This will boost the temperature of the cold exterior air with the Geo-Exchange temperature from the basement envelope air cavity; therefore the earth’s temperature will assist the home’s winter heating needs.

Due to the phenomenon of “Thermal Lag”, the basement structure now has become a thermal heat sink and storage unit, assisting the performance of the building’s heating and cooling system. The basement structure and adjacent earth, during the summer, will be cooler than normal due to the winter’s heat extraction cycle, and it will be warmer than normal at the beginning of winter, due to the dumping of heat during the summer. This results in thermal energy lag effect in the foundation and soil, which assists the home’s heating and cooling.

Our goal is to make our heating and cooling system a “passive / hybrid” / geo-exchange system, eligible for geo-thermal federal tax credit, by illustrating a new and efficient system of energy for our homes.

James Phillip Wright AIA

Energy Architect

Case Study Home # 5

Continuous Whole Building Ventilation

Geo-Exchange Crawl Space Energy

Alamo, California

The purpose of this study is to establish the Earth’s thermal energy contribution to the home, by documenting the energy performance when fresh air ventilation systems are incorporated.

The 1980’s one story 7,000 s.f. Mediterranean residence, with 6,500 sf crawl space has been renovated with “Passive House” techniques incorporating a Mechanically Ventilated Crawl space,“Continuous Whole Building Ventilation,”and air sealing the building envelope for indoor air quality code requirements. The home had been gutted to the framing and fully air sealed with spray foam at the roof, rafters, walls, and crawl space rim joists. A radiant barrier insulative plywood was used for the roof framing, and the attic space is now ventilated as part of the conditioned home. We replaced the existing network of ducting, sealed up the exterior crawl space vents, insulated the skirt walls, and installed a continuous ground vapor retardant barrier for code compliance.

We have two separate HRV units which will operate independently, but will be linked together for seasonal energy transfer only. One for the crawl space and the other for the living space. The contained energy of the crawl space will now create a geo-thermal “buffer space” between the home’s conditioned space, and the outdoors. The HRV maintains the geo-thermal advantages of the crawl space, while the other assists the heating and cooling of the home. In the peak heating and cooling season, the conditioned crawl space’s stale air pre-conditions the main house HRV’s fresh air, using the crawls space energy for cooling in the summer and heating in the winter. In addition to the thermal benefits, the separate system will improve the air quality and health of the building’s occupants, due to the negative air pressure created in the crawl space. Our systems now jointly harnesses the Earth’s natural “Geo-Solar” energy in thistemperate crawl space.

For this study, we are monitoring the utility load in comparison to the load prior to the encapsulation and mechanical modification.We will compare this data to the new results after each season. Our goal is to make our mechanical system, a “passive / hybrid” / geo-exchange heating and cooling system, eligible for the geo-thermal federal 30% tax credit, by proving how much they can reduce the energy consumption of our homes.

James Phillip Wright AIA

Energy Architect