Energy Recovery Ventilator

RainShine is equipped with an energy recovery ventilator that draws air from areas of the house typically exhausted to the exterior, efficiently recovers heat from the exhaust stream during cold weather and pre-cools and dehumidifies incoming air during hot, muggy weather. Indoor air quality (IAQ) is improved and the risk of moisture related damage to the house is reduced. 
RainShine’s exterior envelope is airtight to reduce air and moisture infiltration. The ERV thus provides a controlled method of moving fresh air into the house, dehumidification, removal of stale or contaminated air and reclamation of energy invested in exhausted conditioned air. 

The ERV operates through a dedicated ducting system, replacing bathroom exhaust fans as well as Laundry exhaust. Outdoor air is warmed close to room temperature with heat that would otherwise be lost with the exhaust air. Water vapor transfer moderates extremes in humidity levels which helps prevent moisture damage or over-drying of the house.

GeoThermal Heat Pump

RainShine’s ground source heat pump system takes advantage of the steady state temperature of the earth for heating and cooling. In winter heat is extracted from the earth and delivered to the house. In summer heat is removed from the house and absorbed by the earth. Through the heat pump system the earth’s stored energy is accessed with minimal energy expenditure.

Well system: Because of the RainShine limited site area a closed vertical loop system was employed to access steady state temperatures. For the vertical system, 5 wells (approximately four inches in diameter) were drilled approximately 200 feet deep. Two high-density polyethylene pipes were installed in each of the holes and are connected at the bottom with a U-bend to form a loop. The vertical loops are connected with horizontal pipe (via a manifold), placed in trenches, connected to the heat pump in the basement and filled with an environmentally friendly antifreeze/water solution that acts as a heat exchanger. All joints were heat-fused and pressure-tested before and after installation. The majority of the depth of

RainShine’s wells were drilled through solid granite, an excellent conductor of heat thus positively impacting the efficiency of the system. The bores around the vertical loops in the wells were filled with bentonite clay.

Heating: In heating mode, the geothermal system uses the closed loop well system to extract heat from the ground. The heat pump takes heat from the loop and distributes warmed air through a conventional duct system.

Cooling: In cooling mode, ducted air is cooled by reversing the heating process. Instead of removing heat from the ground, the heat pump extracts heat from air flowing through the ducts and dumps it in the heat sink of the loop wells.

Hot Water: Desuperheaters transfer excess heat from the geothermal heat pump’s compressor to a hot water tank. In the summer cooling period, the heat that is taken from the house is used to heat the water for little cost. In the winter, water heating costs are reduced by about half.

Geothermal heat pumps save money in operating and maintenance costs. While the initial purchase price of a residential GHP system is often higher than that of a comparable gas-fired furnace and central air-conditioning system, it is more efficient, thereby saving money every month.

Unlike standard heat pump compressors that can only operate at full capacity, RainShine’s two-stage scroll compressors operate close to the heating or cooling capacity that is needed at any particular moment. This saves large amounts of electrical energy and reduces compressor wear. Two-stage heat pumps work well with RainShine’s zone control systems using automatic dampers to allow the heat pump to keep different rooms at different temperatures. RainShine’s heat pumps are equipped with variable-speed motors on their fans (blowers). The variable-speed controls for these fans keep air moving at a comfortable velocity, minimizing cool drafts and maximizing electrical savings. It also minimizes the noise from the blower running at full speed.

Rainshine’s geothermal system is eligible for a $2,000 state tax credit and a $2,000 federal tax credit.

Please see the simple diagram below taken from this informative website.

Ground-source (geothermal) eat pump in cooling mode.

Ground-source (geothermal) eat pump in heating mode.

Lighting System

100% of the light fixtures, lighted vanities, bulbs and ceiling fans selected for interior and exterior use in this project have an Energy Star Label or qualified equivalent energy consumption (through use of LED light fixtures and bulbs). This exceeds code requirements as well as the requirements of the Energy Star Advanced Lighting Package (ALP), which is 60% Energy Star qualified hard-wired fixtures and 100% qualified fans. Additionally, other benefits are:

A. The projected life of the LED bulbs is 50,000 hours to 60% lumen maintenance compared to 7,000 hours for CFL bulbs.

B. Total wattage and thus energy consumption is less for the LED fixtures in this project than comparable fluorescent fixtures (see attached spread sheet).

C. LED bulb components contain no toxic materials and are more easily recycled than CFL bulbs.

D. Reduction in installed wattage reduces cost of installed electrical infrastructure (service size, panel size, number of circuits, wiring size, control devices).

E. LED bulbs and fixtures provide more manageable tools for lighting applications. For example, the Cree XRE par 30 bulb is available with controlled beam spreads of 15, 25, 40, 60, 80 and 120 degrees providing more control and thus, in this application, fewer fixtures required to achieve lighting goals.

A similar code compliant house using conventional incandescent fixtures can expect annual lighting costs of $1,479. Rainshine’s lighting system projects annual lighting costs of $295. The spreadsheet below demonstrates the savings.

Sustainability for LEED

Sustainable features include:

• Concrete foundation walls with high fly ash and slag content substantially reducing requirement for high-energy investment Portland cement. 100% recycled content paperboard forms were used. Capillary breaks between all footings and foundation walls.

• Cement-free natural hydraulic lime stucco foundation wall finish.

• Foundation drains and vertical drainage system manufactured from 100% post-industrial recycled content. Low VOC cold applied water-based foundation waterproofing. Post industrial recycled content foundation protection board. Low VOC form release agent.

• Steel beams, columns and reinforcing bars manufactured locally from 100% recycled content.

• Wood floors and interior trim from local, salvaged heart pine.

• Cabinets and built in storage millwork manufactured from zero-VOC 100% recycled content particle board.

• Recycled steel industrial utility cabinets.

• Cabinet countertops manufactured with high post consumer recycled material content.

• All ceramic and glass tile manufactured from salvaged or recycled materials.

• Zero VOC interior and exterior paints, stains, and floor finishes.

• Zero VOC adhesives, sealants and form-release agents.

• PVC free, recyclable solar shades.

• Interior area rugs manufactured from post consumer recycled carpet.

• Low VOC wood sub-flooring and sheathing.

• Highly reflective and recyclable TPO roofing.

• Low VOC rigid roof and basement insulation.

• High efficiency, HCFC- and formaldehyde-free Icynene® wall insulation.

• Locally sourced, high durability, low VOC fiber cement siding.

• High durability cellular PVC exterior trim.

• Locally sourced exterior decking manufactured from post consumer reclaimed plastic and waste wood.

• Driveway wheel strips from re-purposed brick salvaged during site demolition.

• Landscape strips, walks and borders from site demolition salvaged and crushed concrete and locally sourced salvaged crushed slate roofing.

• Bicycle rack and casual stepping stones constructed from locally sourced recycled granite curbs.

• Landscape rain garden swales planted with plants tolerant to submersion designed to manage rainwater runoff.

• Impermeable surfaces, including roofs, totaling less than 10% of site area.

• Full site xeriscaping with native, drought tolerant, non-invasive plants, no turf and no irrigation system.

• Extensive use of nontoxic pest control systems.

Energy Consumption for LEED

Active techniques to reduce consumption of energy include:

1. Two two-stage zoned ground-source heat pumps provide heating and cooling. The heat pumps provide air distribution that will adjust to the variation in loads throughout the areas of the house throughout the day and will provide both temperature and dehumidification control.

2. A desuperheater is coupled to each of the two geothermal heat pumps and heats water with energy that would otherwise be given up to the heat sink of the closed loop wells. When the heat pumps are operating, hot water is virtually free. Hot water is stored in high efficiency hot water heaters that serve as backup hot water generators when the geothermal heat pump system is not in operation.

2. An energy recovery ventilator provides balanced introduction of fresh filter/conditioned air and reclamation of invested energy from air typically exhausted from bathrooms, kitchen and laundry.

3. Lower capacity high efficiency two-stage zoned geothermal heat pumps will provide the necessary heating and cooling with controlled airflow to the zones that require conditioned air which can be as low as a few hundred cfm per zone. For most of the year 1200 cfm provides required conditioning, 2000 cfm on the very hottest or coldest days compared to 3,600 cfm required in code compliant designs.

4. A net-metered roof mounted 3.1 kilowatt photovoltaic system. The system, consisting of 18 high-efficiency monocrystalline photovoltaic modules, is mounted on the south-facing portion of the butterfly roof. Through the Georgia Power Net Metering System, all power generated from the photovoltaic system is independently metered and made available to Georgia Power for it’s Green Energy program. Georgia Power pays 17.4 cents per kilowatt hour for power generated by the system. Energy consumed by the house is obtained from the grid at 8.64 cents per kilowatt hour and is monitored by a separate meter. As incentive, this system has received a $10,500 state tax credit and is eligible for a $2,000 federal tax credit.
The system was installed and activated shortly after completion of framing and roofing. It generated and sold power during the remainder of the construction period.

5. Energy Star appliances.

6. All light fixtures employ LEDs or are fluorescent Energy Star rated and, in total, consume 1/10 of the power of a similar code compliant house using conventional fixtures.

Passive Solar Techniques

Passive solar techniques used include:

1. Exterior bearing walls are constructed of 6” wood studs compared to more conventional 4” wood studs. The wall cavity is filled with Icynene®, a water-based. highly efficient foam insulation and sealing system that contains no formaldehyde, CFCs or HCFCs.

2. Eaves overhang all walls and glazing of the structure. Eaves are more extensive on the south façade, less extensive on the east and west where microclimate tree canopy effects take over early and late.

3. Roofed porches and screened porches shade the house and glazing on portions of the south, east and west walls.

4. Solar “eyebrows” shade south facing glass at the Living Room. Interior light shelves bounce light into the interior reducing light fixture dependency.

5. Interior roller solar shades screen east-, west- and south-facing glass where not protected by eaves, eyebrows or porch roofs.

6. Operable windows provide cross ventilation and, via remotely operated clerestory windows, create a stack effect thus allowing the occupants to enjoy the benefits of their mid spring/fall climate while reducing reliance on cooling systems.

7. Basement exterior walls are insulated and are not vented.

8. Significantly lower heating and cooling loads resulting from passive design reduce hvac airflow in the home thus reducing drafts and excessive temperature and humidity fluctuations.

9. New deciduous plantings will assist in shading the house in summer and allow sun to penetrate in winter.

10. Recognition in the formal design of the house of the site microclimate and morning/afternoon shading provided by the existing tree canopy.

11. High efficiency glazing - SHGC of 0.36 and winter/summer “u” value of 0.24/0.21

12. The design of the home results in significantly lower heating and cooling loads which reduce hvac airflow in the home and thus reduce drafts, excessive temperature and humidity fluctuations.

LEED for Homes

RainShine is being constructed under the LEED for Homes Program Pilot Rating System. LEED for Homes is an initiative designed to actively promote the transformation of the mainstream home building industry towards more sustainable practices. LEED for Homes is targeting the top 25% of new homes with best practice environmental features and is a collaborative initiative that actively works with all sectors of the home building industry. This home’s performance in regard to sustainable practices will be measured in eight different resource categories: 

1. Innovation and Design Process

2. Location and Linkages

3. Sustainable Sites

4. Water Efficiency

5. Improved Energy and Atmosphere

6. Use of environmentally preferable Materials and Resources

7. Indoor Environmental Quality

8. Public Awareness and Education. 

The LEED for Homes rating system works by awarding credits for different aspects of environmental design in each of the above categories. The level of performance achieved in the above categories is separated into four performance tiers. LEED for Homes will rate this home at one of the following levels: Certified, Silver, Gold or Platinum. Levels are awarded according to how many points the home achieves in the Rating System. The goal of the RainShine house is to achieve the Platinum level. We anticipate that this house will consume less than 50% of the energy that would be consumed by a similar home built to the standards of the International Energy Conservation Code.

This residence employs many passive and associated active techniques designed to reduce consumption of energy. Additionally, the house employs an extensive list of environmentally preferable materials from salvaged, locally sourced, to recycled to those with low or no volatile organic compounds, each representing lower energy investments, lower contribution to off-gassing and environmental pollution, reduced energy investments in shipping, enhanced durability, etc. Furthermore, specific construction techniques and programs have been implemented to reduce on-site wastes, increase recycled construction waste and minimize the use of materials through efficient framing systems.