A home Heliocentric has been working on for the past year or so came to a certain level of completion last week as the builder got things finished for the Park City Area Showcase of Homes which opened August 21.
To ramp things up, I embraced my budding PR skills and sent press releases to all the local news outlets in anticipation of a press conference we held at the home August 19. I got all our marketing materials pulled together and even managed to get shirts embroidered with our logo for our whole team.
There was a good turn-out at the press conference and we got some nice pieces on TV and in the newspaper.
And, my goodness, the opening day of the home show on August 21 was a whirlwind! 337 tickets were turned in that day and there was a steady of stream of visitors, many of whom were particularly interested in the green features of the home we were responsible for. Yay!
More press seems likely to follow and there are still two weekends of the home show and another weekend of the Utah Solar Tour next month. Good times!
So what are all these amazing green features, you ask? Well, this home is really very, very cool (or warm, depending on the season – thanks for the punch line Alyssa!). The main thing is this house is a passive solar house that makes 90%+ of its heating and cooling energy just from sitting there, passively using the sun's energy. The remainder of its energy needs are produced on site using sophisticated solar thermal and solar electric panels, thus making the home a "net zero" energy producer – it produces as much energy as it uses. Here's a list of features:
The Green Guide to the O'Meara Home
1. A 6.9 kW photovoltaic array installed on the barn will be tied to the grid, providing all the power needs for this home and clean power back to the grid to be sold to the neighbors.
2. Before construction began, a site assessment was completed and the home was carefully oriented for passive solar gain. Proper site orientation is critical for a passive home to work properly. As an added bonus, the site orientation and glazing design allowed for fantastic views!
3. Super-insulated and limited thermal break Structural Insulated Panels (SIPs) were used to construct the walls and roof of the home.
4. For passive solar designs to work, air infiltration must be tightly controlled. The building was air-sealed at all potential air penetrations and meets the PassivHaus Institute’s maximum requirement of 0.6 air changes at 50 pascals of air pressure.
5. Glass is a critical component of any passive solar home. There must be a balance of solar gain and high insulation to gather and retain solar resources. The 4-pane windows and glazed doors in this home were manufactured by Serious Windows, using a custom high solar gain glass designed by Heliocentric. The fiberglass frames are in-filled with foam insulation. The result is that the windows have an average insulating value of about R-12.
6. In a unique application designed by Heliocentrirc, Phase change wax was pumped into tubes in the northern concrete walls to add to the thermal mass of the home and peg the temperature of that mass at a comfortable 70° F. A lot of energy is stored in the phase change between liquid and solid. Phase change waxes made from renewable crops like soy and coconut are designed with melting points at human comfort temperatures and can be used in a number of different applications in passive solar buildings.
7. A home controller interface represents the “brains” of the home. It connects directly to a whole-home custom controller (built by Heliocentric) in the mechanical room. This controller integrates and optimizes all the systems in the home to keep the home comfortable using the least-cost technology available. Sensors inside and outside the home continuously feed data about temperature, humidity, respiration, condition trending, etc. to the controller and the controller uses this data to adjust things like the ventilation rate, the automatic window openers, the distribution of the radiant floor loop loads, and so on. The homeowner can use this interface to adjust thermostat settings, to view current conditions within the home, to view a map of the system, to view historical trends within each component of the system, and to make adjustments to other set points and system functionality.
8. This home makes best use of every resource. The 10,000 gallons of on-site water storage required by the fire marshall serves double duty as a heat sink. Custom-designed and site-manufactured heat exchangers are installed in the storage tanks, connected to the solar thermal panels and controlled by the whole-home custom controller. In the summer, when an abundance of hot water is produced by the solar panels, the heat is prioritized to the stratified solar water tank in the mechanical room for showering, washing, etc. Next, the hot water is sent to the underground insulated storage tanks to transfer its heat to the stored water. These tanks can store 3+ months of home heating to be used in the winter months.
9. Heating and cooling are delivered to various areas of the home through radiant tubing in the floors. The radiant loops return to the mechanical room and the whole-home custom controller decides where adjustments need to be made in temperature and how to move the water using high-efficiency pumps from one location to another. Thus, the radiant loops allow the passive solar to take best advantage of the thermal massing and keep the home cool in summer and warm in winter with minimal external energy inputs.
10. The roof supports 260 square feet of solar thermal panels that produce on average 200,000 BTU energy per day. This hot water will be used for domestic hot water as well as for heating the home.
11. Sensors in the floor work in conjunction with the whole-home custom controller to identify trends in temperature differentials between various locations in the home. The controller operates high-efficiency pumps to redistribute the gained solar heat from “hot” zones to “cool” zones. Thus the home takes best advantage of its thermal massing and solar gain, keeping the whole building comfortable at a minimum energy output.
12. CO₂ sensors measure varying respiration levels in the home and communicate with the whole-home custom controller, which then adjusts the ventilation rate from the HRV. In this way, plenty of fresh air is available when the family has houseguests or a party.
13. Solar wells (custom-designed and site-installed plumbing tubing) are installed behind the metal siding on the south side of the home to preheat domestic hot water before sending it to the stratified tank, reducing the load on the solar thermal panels and the instant-on hot water heater.
14. The 210 gallon stratified solar tank is more functional than a typical hot water heater. It has a multitude of input options to draw hot water from numerous sources, like the solar wells in the south side of the house, the solar thermal panels on the roof, and the underground heat sinks behind the home. It then “stratifies” the inputs from these various heat sources with hottest water at the top and coolest water at the bottom. This stratification allows the solar thermal panels to work more efficiently by transferring their heat to cooler water, and also means there is always domestic hot water available since the entire tank does not have to be heated at once or completely drained before heat can be added to the system.
15. The office tower in the center of the home, outfitted with automatic window controllers operated by the whole-home custom controller automatically opens the windows for nighttime flushing in the summer to keep the home cool and comfortable.
16. Serving triple-duty is a 5000-gallon underground cistern fed by a site-built well and a rainwater catchment system, connected to the radiant loops in the home and utilized for cooling and irrigation of the tree nursery. The whole-home custom controller monitors and adjusts the level of the tank using an ultrasonic sensor. It reduces the water level during the rainy season to allow for surge capacity, and increases the water level during the hot months to allow the custom-designed, site-manufactured radiant cooling loop to transfer the cool temperatures of the ground water into the home. No air conditioner needed to keep this home cool and comfortable all summer long.
17. A rainwater catchment system is installed to recover roof-top rainfall and direct it to a 5000-gallon underground cistern. The water is used for both summertime cooling and a low water-loss drip irrigation system for the tree nursery.
18. At the end of winter, when the underground solar storage is depleted and the solar thermal panels are not quite keeping up with demand, a high efficiency instant-on hot water heater augments the passive solar system.
19. All toilets in the home are high efficiency dual flush toilets.
20. Heat exchangers at the shower drains recover the heat from the water.
21. High-efficiency lighting fixtures were used throughout the home, most of them LED.
22. During the construction period, up to 95% of waste was recycled. The family intends to continue the trend and recycle their own waste.
23. The yard is landscaped with native and low-water use plants, fitting with the natural beauty of the environment and keeping irrigation needs to a minimum.
24. The walkway is a permeable durable concrete walk that allow rainwater to penetrate to the surrounding vegetation.
25. The driveway is made of a recycled crushed asphalt product that reduces the dust impact over a standard gravel drive and allows proper drainage, preventing erosion and run-off problems.