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Project

Sungazing House Puts Sun to Work (Utah)

Credits: ©2011 O'Meara Sungazing House

Built with foot-thick structural insulated panels, the Sungazing House in Park City, Utah, effectively mitigates extreme temperature swings using passive solar design as well. The passive design employs a 16-inch concrete wall with an innovative custom phase-change wax to increase the wall’s thermal mass. A 6.4 kW grid-tied photovoltaic system on the barn produces power to spare for all the home's electricity needs. Owners, Kevin and Svetlana O'Meara, set a goal to blend architecture with the surrounding terrain, and utilize the power, energy and movement of the sun. This net-zero home has walls that deliver R45 and roof at R60. Due to the construction methods, the project did not require even one dumpster for waste. The home incorporates eight inches of rigged foam insulation under the basement floor, radiant heating, photovoltaic solar panels, quadruple-glazed windows, heat recovery drains with no moving parts, LED lights, and more. The home’s two 5,000-gallon tanks - required by the local fire department due to the home’s location far from a hydrant - are surrounded by 12 inches of rigid foam insulation (R48) and buried underground to store heat energy. Corrugated stainless steel tubing is bent around hand-built frames to make three heat exchangers in each tank. This system provides hot water to the heating system during winter when the ten solar hot water panels would have difficulty heating enough water for space heating, domestic hot water, and a hot tub. According to owner Kevin O'Meara, the south facing metal siding has PEX tubing under the metal, atop a shiny metal backing, to provide additional solar water heating. Eight thermostatically-controlled electronic window openers are strategically placed to maximize cold air intake and hot air exhaust. Motorized solar shades are also thermostatically-controlled. The radiant tubing system is also programmed so that heat/cold can be transferred from one area of the home to another; for example if the upstairs is heating up and the ground floor is cool, the system knows to circulate the fluid to balance temperatures. The airtightness of the home rates below 0.6 ACH at 50 Pascals. The Sungazing House is built to PassiveHaus Institute standards, is an Energy Star Home, and has earned NAHB Emerald and Platinum LEED-Homes certifications. (Scroll to bottom for additional resources)

 

Sungazing House Aerial2

Built with foot-thick Premiere structural insulated panels, the Sungazing House in Park City, Utah, effectively mitigates extreme temperature swings using passive solar design as well. The passive design employs a 16-inch concrete wall with an innovative custom phase-change wax to increase the wall’s thermal mass. ©2011 Premiere SIPs

Nature by Design
To settle in Park City, Utah is to celebrate nature in large measure. Some residents take that to heart more than others. Built in 2010 by Kevin and Svetlana O’Meara, the Sungazing House was designed and constructed to honor the power, energy and movement of the sun. The 3,700 square foot home, intimate by Park City standards, perches on the south slope of the Wasatch Mountains above Snyderville Basin. Consciously designed for energy efficiency and sustainability, the home is likely the first Platinum LEED certified residence constructed in the state of Utah. As important, it follows the principles of the Passive House movement, with energy efficiencies in all systems including the added efficiencies of an airtight structure. “The house is kind of like architecture meets eco-warrior,” says owner Kevin O’Meara.

Designed by architect Jean-Yves Lacroix as two rectangular structures connected by a three story tower, Sungazing House invites the outside in. Mountain views dominate the landscape from every window and deck. Solar thermal panels atop the roof harness the sun’s energy for heating and domestic hot water.

With the knowledge that it is three times more cost effective to conserve rather than create energy, the O’Meara’s set out to build the most energy efficient home possible. Research led them to the PassivHaus movement, which originated in Germany. The PassiveHaus building principles include airtight construction, super insulation and high performance windows. House built to the PassiveHaus standard uses only five percent of the energy of a conventionally built house. Currently there are 2500 passive homes built to PassiveHaus standards in Europe but less than 20 in the United States. PassiveHaus principles have also been adapted to modest and low income housing.

Sungazing House’s energy efficiencies include Structural Insulation Panels (SIP), which were used for wall construction and help meet the stringent airtight and high insulation requirements of PassiveHaus design. Quadruple pane windows punctuate the envelope for high U-value glazing.

The residence is an interactive solar house. Blinds and windows are synched with thermostats to open and close automatically to control indoor temperatures. Two 5,000 gallon underground water tanks are situated behind the house to store heat energy. Heat recovery drains which have no moving parts and pay for themselves in five years’ time, reclaim the heat from drain water to preheat shower water.

The Sungazing House’s square footage is realized in an open floor plan that is spacious yet with intimate areas. It includes three bedrooms plus master bedroom wing, four baths, a state-of-the-art media room, playroom, spectacular mountain-view kitchen and companion great room. A third level den/office space is a bonus of the connecting tower design. In the playroom, whimsical cubbyholes are painted in a rich copper color with inset LED lights that punctuate wall space for display and storage areas.

“We wanted to blend energy efficiency with architecture that was molded by the landscape and the sun,” says O’Meara. “Finding the way has been like exploring a vast system of canyons without the benefit of maps. We remained open to all possibilities, did our research and assembled a remarkable team of construction partners. We believe we have the most energy efficient home possible that also celebrates the sun and nature by design.”

From Legos to Lacroix
After finding the land, the decision to build Sungazing House became more complex. The O’Mearas looked at plenty of house plans in books and online, but couldn’t find any to meet both their functional desires and aesthetic taste. The logical decision was to design it themselves. Next came libraries and bookstores, friends, and a borrowed collection of many years’ worth of magazines. The more they studied, the more they realized the tremendous passive solar potential for the home. They wanted a “smart house”. One that would let the natural elements dictate the design. They started modeling houses with Legos, then advanced to Google’s “Sketch Up”, and finally jumped into architectural software.

Then “smart” really kicked in. It was time for a real architect.

Enter architect Jean-Yves Lacroix, renowned for his luxurious, exclusive properties designed near Park City ski areas. Lacroix embraced the concept and ideals of Sungazing House, but had yet to be presented with an opportunity to design such a home.

To map the most favorable location for the house on the site, a composite image made from a Google Earth satellite image with a topographic overlay was created. The method allowed for a driveway that was compliant with multiple Summit County regulations, while minimizing the impact to the existing scrub oak trees on the site. Prevailing wind direction to decrease snow drifts and maximize sun exposure for snow melt was accommodated. Sun angles and simplicity drove the design process.

The roof design allows the sun in through windows to reach the back wall of the house at noon on winter solstice, while keeping the interior of the house shaded during the summer months. To change the design from an aesthetically undesirable long straight house, the two pods had been slightly angled to create architectural interest. Lacroix’s solution to join roof angles was to create a three-story tower to join the two pods. It is dramatic, solved the roof puzzle, and added a small bonus “Eagle’s Nest” office nook as a third level. The tower was also designed to allow excess heat to rise up and out of the house via a ceiling fan and windows on all sides, as is done in other desert environments.

Promotional pricing was offered by many material manufacturers if the house was built for green or energy efficient certification. Many programs demanded rigorous energy efficiency to achieve the highest levels, and in their research, the O’Mearas realized that they had already accommodated many of the certification requirements. It is believed the home is Utah’s first LEED platinum/ NAHB Green Build Emerald certified residence.

Builder
The O’Mearas considered doing a lot of the construction work themselves, as Kevin had some experience building and remodeling. However, since they both worked full time, with growing kids that need attention, too, the "smart" way wins again. The O'Mearas talked to nearly a dozen contractors, before selecting Garret Strong and his company, Tall Pines Construction, who brought ideas that have enhanced the home both functionally and aesthetically.

The Building Envelope
The building envelope includes the walls and roof - the shell of the house. The building envelope has many attributes both aesthetic, and functional. The aesthetics are purely subjective; however the functional properties can be objectively measured. Paramount among these functional properties for an energy efficient house are its insulation, measured in R values and its air tightness, which is a measurement that has not been commonly measured in home construction in the United States. The air tightness is measured after the house is built by closing all the windows and doors, then replacing the front door with a “blower door.” The house is pressurized and the amount of air that escapes is measured.

Blower Door Test
R-values measure the resistance to the flow of heat across a barrier - as thermal dams. Higher R values imply that less heat is working its way through your dam…which is the wall of your house. Lower air infiltration is akin to reducing the water leakage between the stones that make up the wall of the dam. So if you have a great product to hold back the water of your dam (R value) but it leaks at the joints (air infiltration) you still have lost a lot of water (heat). The R value is primarily determined by the type of insulation used and its thickness, while the air infiltration is largely determined by construction methods. The concept of minimizing heat loss by controlling both the R value and air infiltration constitutes the fundamental principles of the PassivHaus movement. The PassiveHaus movement started in 1991, founded by Dr Wolfgang Feist of Austria, who has developed sophisticated software based on these principles, to reduce home energy needs to five percent of a typical house. The exterior walls and roof of the O’Meara house are made of Premiere structural insulated panels (SIP panels) which are made of two layers of OSB (orientated strand board which is manufactured from wood flakes) that are 7/16-inch thick and separated by 11 and a half inches of EPS (expanded polystyrene or Styrofoam). They have an R rating of 45 and the roof has an additional layer of four-inch EPS to make it R 60. They were manufactured based on Lacroix’s architectural plans at the Premier panel factory and arrived, like a giant jigsaw puzzle, with all the window and door openings cut into the panels.

The team had examined many different options for wall construction, including conventional construction using 2X6’s with fiberglass insulation, insulated concrete forms (ICF’s), straw bales, dry stacked masonry blocks, double wall designs, insulating concrete, and various other “blocks” made from mixes of concrete and recycled materials. Kevin’s brother Dave steered him to the Oak Ridge National Laboratory website where he learned about various house construction technologies. ORNL has built identical houses from various materials and techniques and then intensively studied their performance. It was here that he discovered trustworthy information on various options. For example, he learned that typical construction as represented by 2x6 stud wall framing which is usually thought of as R19, really delivers only R13 after accounting for the typical air infiltration around the fiberglass insulation and the thermal breaks caused by the wood itself.

Houses account for 21 percent of energy expenditures in the US, and almost half of that is for heating and air conditioning. A typical Park City (in 2011) home spends about $300 per month for heating. Depending on the reference you use, it is believed that for every dollar you invest in reducing your energy use you save two to three times what it would cost to produce. It became obvious that a tight, well insulated envelope was critical. Their first bid was for six-inch thick SIPs, which are commonly used to achieve R-22 walls. They had the bid redone for the thickest panel - 12 and a half inches – and found the cost was only about 10 percent more. So, going with the thick panels, which we dubbed “Fat Boys” after the ice cream sandwich, were a “no brainer”.

SIPs lend themselves to very airtight construction. The ORNL tested a four-inch SIP vs. 2X6 wall construction that showed a marked difference, 9 vs. 126 cfm. Since SIPs are precut at the factory, on-site waste is drastically reduced, too, and therefore the project did not require a dumpster for construction waste.

Footers and Foundation
The function of the footers and foundation is to anchor the house to its location and support the weight of the house. The SIPs wall construction would sit on the foundation, and because it doesn’t lend itself to the on-site modifications that can be done with traditional framing it was important to get the foundation right from the beginning. In climates where freezing occurs, the foundation must also be designed to prevent “frost heaving”. Park City experiences cold and freezing weather, and local codes dictate that the footers be buried 36 inches below grade. An alternative method to prevent frost heaves is called shallow-depth frost-free footer design, first popularized by American architect Frank Lloyd Wright in the 1930’s. It uses “wing” insulation around the outside perimeter of the footers. The theory is that as heat escapes from under the house it spreads outward. By putting 4 X 8-foot sheets of two-inch EPS (expanded polystyrene better known as Styrofoam) around the outside perimeter of the footers, the heat is trapped closer to the footers, keeping them warm and free of frost. This saves excavation expense, saves on concrete, and better insulates the house – and this project was the first shallow-depth foundation to be permitted in Summit County.

The footers and foundation were composed of concrete that used a 50 percent fly ash mixture which reduced the embodied energy of the concrete by recycling a byproduct of coal-fired electric plants. This mixture has a final cure strength that is twice as strong as the conventional concrete mix, although it also has double the cure time. Concrete manufacture accounts for five to ten percent of world energy use.

EPS is placed not only on the sides of the footers, but also underneath, which prompted the Summit County inspector to request engineering documents. Because of the EPS supports a high amount of weight under the footers, the project installed extra-dense EPS and extended the footers over a larger surface area than typical to spread the pressure out over a large area. Additionally the sides and tops of the footers, as well as the foundation walls, were wrapped with two inches of EPS, and the narrow gaps between pieces of EPS were foamed to prevent heat sinks.

The foundation is waterproofed with environmentally-friendly Ecobase instead of the traditional black tar-based material. A polymer-based gasket called “ecoseal” replaced the traditional thin blue “bubble wrap” called sillseal coupled with treated lumber. This allowed a more affordable, airtight and durable seal between the foundation and the SIPs.

Eight inches of EPS (R32) was placed on the ground before pouring the basement cement floor to help reduce heating loads. Typical practice is to pour the concrete directly onto the gravel underneath, even if radiant floor heating is used. The temperature of the soil beneath a house is about 55 degrees, while the temperature inside a house is commonly 70-72 degrees. With radiant heating in floors, such as this project, the fluid is typically heated to 80-85 degrees. The laws of thermodynamics tell us that more of the heat will be “sucked up” by the ground than the air inside the house because of the larger temperature differential. 

The Thermal Mass Wall
The large cement wall on the north side of the house has a total length close to 100 feet, 18 and a half feet high, and 28 inches thick to provide thermal mass.

Thermal mass acts to moderate the temperature swings inside a house by absorbing the excess heat allowed into the windows during the day and then releasing it back into the house at night as it cools. The O’Mearas wanted to maximize such passive solar performance of their house, so they depended on information from books like The Solar House by Daniel Chiras and The Passive Solar House by James Kachadorian. Using the information from these books, the house was designed to have a lot of south facing windows but thermal mass was needed. Since there isn’t much thermal mass in SIP panels, or for that matter typical frame construction, they were originally considering a concrete wall 24 inches thick.

Troy Harvey of Heliocentric, an energy and environmental engineering firm, introduced the team to two new concepts that made the wall perform better, cheaper, and become more environmentally friendly. He recommended the 50 percent fly ash mixture (discussed in the footer/foundation section above) and the use of a Phase Change Material (PCM). (Phase change refers to having a substance go from a solid to liquid, or liquid to gas…or back.) To utilize PCM, one-and-a-half-inch PVC pipes were located inside the wall’s concrete forms, spaced every 16 inches, closer to the interior surface, and filled with paraffin wax. The tubes were filled with three 55 gallon drums of wax that is designed to melt, or phase change, at a desired room temperature. The wax-filled tubes allowed us to narrow the wall to its present 16 inches, from the original 24-inch thickness. The thickness of the wall also allowed them to eliminate using metal beams in the shear walls, which saved money in construction costs, and reduced thermal bridging or heat loss. The net effect of using both the thermal mass and the PCM is that the temperature inside the house becomes “locked” within the comfort zone set between 68-72 degrees, without any additional energy source.

In addition, the north side of the wall is bermed and contains four-inch thick EPS and plastic rebar at these thermal breaks instead of metal rebar to further reduce heat loss where the wall extends beyond the thermal envelope of the building.

Relevant books:

The Passive Solar House
The Solar House


Resources

Tall Pines Construction (Utah)

Heliocentric (Utah)

LaCroix Design

Sungazing House in Utah

Passive House (USA)