Design and Construction of Net-Positive Energy Housing
Park Management Team, John Day Fossil Beds National Monument, National Park Service, Oregon.
Project Point of Contact
The Park Management Team at John Day Fossil Beds National Monument successfully pursued building an unconventional, state-of-the-art zero-energy home as a replacement for the ranger residence at the remote Painted Hills Unit.
The original residence was constructed by the JOB Corps in Moses Lake, Washington in the late 1970s. Though adequate for a while, it reached the end of its useful life. It was costly to maintain, did not have a foundation and was build on expansive soils, and was not energy efficient. The park management team, as part of its efforts to be operationally carbon-neutral, decided to pursue building an unconventional, state-of-the-art zero-energy home as a replacement for the house. Towards that end, they researched the possibilities thoroughly, developed a plan, and submitted a well developed project proposal for programmatic funding to the Pacific West Region. The plan included building a house that would produce more energy than it would use, but focus on the conservation/efficiency side of that equation. An additional goal was that the house would cost no more than a house built using the standard housing designs in the NPS housing program. Since this project involved building nonstandard housing, it bucked the housing guidelines to use standard NPS residential designs under the housing program. Because of this, approval was problematic. However, the Pacific West Region supported the project after the park presented its potential advantages at a regional project review.
In 2009, the project was funded and construction drawings and specifications were fast-tracked. It was contracted and constructed in 2010 using American Recovery Act funding. The house is a 1200-square-foot structure constructed on a heavily insulated concrete slab. It utilizes non-standard construction using structural insulated panels (SIPs) for both walls and roof to provide a very air tight building envelope with extremely low heat transfer. SIP construction eliminates thermal bridging in the exterior walls caused by the wall studs used in standard construction. Because the SIP panels are manufactured to order with all window and door openings pre-cut, there is very little construction waste. Few contractors are familiar with full SIP construction, so the actual building of the house involved significant oversight from the NPS, primarily through the park's contracting officer's representative and park superintendent. Besides non-standard SIP construction, the house incorporates several other innovative energy-saving measures including:
- A heat recovery ventilation (HRV) system that uses exhaust air to heat or cool incoming fresh air to avoid losing energy while providing a constant supply of fresh air. This HRV can also be used as an economizer, utilizing diurnal temperature differences to capture and store heat or cool air in the early morning or late afternoon, depending upon ambient air temperatures. These wide swings of temperature are common in dry environments, but are rarely used to conserve energy in a residential structure.
- Better than Energy Star appliances throughout the house.
- A mini-split, high efficiency heat pump to provide what little heating and cooling that is required.
- Triple glazed, argon gas-filled windows
- Double- and triple-sealed doors to eliminate air leakage.
- A grid-tied photovoltaic system and drain-down solar hot water panels on a south-facing roof, optimally angled for solar gain
The constructed house has a home energy rating (HERS) of -43. This compares to a rating of +100 for an average home constructed to code today, and a rating of +80 for an Energy Star-rated home constructed in central Oregon. What this extraordinary HERS rating means is that the home will actually generate 43% more energy than it will consume. The house also will achieve an Emerald Rating from the National Association of Home Builders through its National Green Building Standards program. This rating is the highest standard of the rating system. Very few homes
can qualify at this level. Meeting this level requires a certified independent third party verifier.
Results and Achievements
The primary and important results of the project are as follows:
- The construction of a very functional residence that is so energy efficient that it generates more energy than it uses.
- Allenergy generated by the project is carbon-free.
- The residence will eliminate utility costs to the ranger that resides there.
- This residence was constructed at a cost comparable to standard construction (approximately $250 per square foot).
- This residence could be a prototype for future housing in the National Park System.
- Constructing this residence exposed local contractors and the public to a new way of building that is far more energy efficient than any they are familiar with.
- Constructing this residence demonstrated the National Park Service commitment to energy sustainability, green building practices, and reducing our carbon footprint.
The techniques, materials, and methods used to construct this residence are directly reproducible and can be used in any national park, wildlife refuge, national forest or other federal agency to construct housing. Similarly, the use of SIPS, HRVs, mini-split heat pumps, and similar materials, techniques, and methods is directly applicable to any facility construction in the National Park System (or elsewhere). Finally, exposing the public to this type of construction furthers its adoption as a new standard for construction and could go very far in reducing carbon emissions associated with residential energy consumption, which represents the largest proportion of energy used in the United States and correspondingly the largest contributor of greenhouse gasses in the country's energy portfolio.