HVAC DESIGN DESCRIPTION
Figure 1. below provides a schematic representation of the HVAC system, home insulation levels and unique air flow design. It does not represent the architectural design or actual scale
of the home but does show the functional elements included in the design. Four independent subsystems are shown with their associated air flows in overlay. A fourth source not shown provides emergency backup heat via baseboard radiant electric appliances. In actual use this backup is not needed unless there is failure of the Geothermal HVAC.
Figure 1 shows the interrelationship between the many aspects of a novel and unique HVAC system. Following is a description of each contributing component:
AIR HANDLING SUBSYSTEM - This system provides air flow to support all the sources of heat and cooling. The major components are:
RETURN AIR PLENUM (green shading) - A novel part of the design is use of the underfloor crawl space as a central return air plenum and minor heat storage area. This space is completely sealed from outside air, water and vermin infiltration. Continually supplied with warm return filtered air from the second floor ceiling it returns the air to the first floor for warming and balancing temperatures throughout the home. Fig. 1 shows the crawl space foundation walls are insulated from the earth by R-12 rigid board insulation while foundation coating and a french drain beside the footer insure water does not infiltrate the wall. A concrete slab covers the floor of the space under which is placed a vapor barrier and beadboard styrofoam insulation. These measures insure the crawl space is a clean energy efficient space through which household air is constantly filtered & recirculated. Also, this plenum provides a convenient space under the entire first floor for routing new wiring and pipes in the event future modifications are desired.
SUPPLY AIR PLENUM (rose shading) - The supply plenum is formed from the second floor joist system comprised of 16" high factory prefabricated and prestressed trusses using 2 x 4 framing lumber. The result is an open air cavity measuring 42' x 26' x 1-1/4' for a total air volume of 1400 cuft, minus the space occupied by truss members. This space is sealed and insulated with vapor barrier around the external perimeter. The air plenum distributes supply air to first and second floors from the geothermal HVAC system without the need for a metal ducting system. Since supply air is routed through structural members, a commercial level fire protection system is added to deactivate the HVAC upon detection of smoke. This prevents the fan system from supplying oxygen to any internal fire.
AIR DESTRATIFIER & FILTER UNIT - This low power fan unit continually draws in warmed air from the second floor ceiling, down flows it through mechanical and electronic filtration elements before discharging it into the sealed crawl space where it is returned to first floor rooms. As such it is an integral part of the passive solar assisted and masonry stove wood heating systems. In addition it increases home comfort by balancing air temperatures throughout.
GEOTHERMAL HVAC SYSTEM - Installed in 2011, this system comprises a WaterFurnace™ Envision series indoor unit served by a 400' deep dedicated well grouted with bentonite. This unit provides 5 units of heat or cooling for each unit of energy required to operate it for an efficiency up to 500%. The highest efficiency fossil fuel system is natural gas which provides 0.98 units of heat for each unit of input energy for an efficiency up to 98%. Clicks buttons below for more information on geothermal.
PASSIVE SOLAR ASSISTED HEATING - The home design maximizes winter heating from solar input by orienting the entrance face due south and concentrating more glass on this face than on the other sides. Click the button below for more information on the installed passive solar assisted heating system.
HIGH EFFICIENCY MASONRY HEATER - The home includes central installation of a masonry heater design used for centuries in Scandinavia and Siberia, hence the common name, "Russian fireplace". This is the most efficient and ecologically clean wood burning appliance available. Click the button below for more information on the installed version which is Finnish in origin.