Case Study Home # 2

Geo-Solar Thermal Storage / Crawl Space Energy

Sonoma, California

High energy costs, comfort needs, and “health” concerns, inspired the renovation of this 1980’s two story Californian Craftsman. This home was designed with two cathedral ceiling spaces and a solar atrium, but it never functioned by the “Home s a System” theory due to its leaky T&G wood ceilings and its inadequate airflow design.  There are two main factors that result in an excessively wasteful home. One is that older homes were built so they leak or breathe health reasons. The second is that the home has very little thermal mass due to its wood frame construction.  In addition this home had great health concerns resulting from significant rodent infestation in the crawl space.  Our energy / health solution converted the existing components of this home using techniques of the “Passive House” design, and integrating “Thermal Mass” as energy storage,

The energy, airflow, and air quality needs of the home retrofit were solved by encapsulating the crawl space, “air sealing” the building shell, incorporating a stratification duct, and introducing “Continuous Whole Building Ventilation”. We introduce fresh air into the building envelop by means of an HRV (heat recovery ventilator), and pre-condition the stale air through the crawl space. The HRV maintains the geo-thermal advantages of the crawl space, while assisting the heating and cooling of the home. We added “thermal mass” as energy storage, in the atrium crawl space chamber. This “thermal mass” is heated or cooled hydraulically using a pump system connected to thermal panels on the roof.  The stale air of the home is then distributed through this chamber and conditioned by the thermal storage.  This “pre-conditioned stale air then conditions the incoming fresh air through the HRV, cutting heating and cooling costs. In addition to the thermal benefits, this system will improve the air quality and health of the building’s occupants, because the dirty crawlspace air never enters the envelope of the building. Our system now harnesses the Earth’s natural “Geo-Solar” energy, in this damp, musty, temperate, crawl space.

We replaced the existing network of ducting, adding new high air returns, mixing the air of upper rooms with the air of the rooms below, creating a uniform temperature throughout the home, and installing an all electric 97% efficient heat pump HVAC unit.

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. My goal is to becoming eligible for the geo-thermal federal tax credit, by documenting the energy reduction to qualify as a “passive” / geo-exchange heating and cooling system.

Concept October 2010  

                Clients & Thermal Storage Pack

                        Heat Capacity Test

       Rodent Infestation in Existing Crawlspace

       Encapsulation and Air Sealing Spray Foam

                        Blower Door Test