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Buildings solar decathlon 2015

Published on August 19th, 2014 | by Amber Archangel

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Technology Spotlight: Ventilation in Solar Decathlon Houses

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August 19th, 2014 by  

1Sun4All.

The U.S. Department of Energy Solar Decathlon communications team presents a series of technology spotlights in the article below that introduce common technologies used in the Solar Decathlon team houses. This article written by Alexis Powers and Carol Laurie, clarifies Energy-Recovery Ventilation Systems.

solar decathlon 2015

Team Ontario used this energy recovery ventilator in its “ECHO” house. Energy recovery ventilation systems help maintain a comfortable indoor environment by recovering 70%–80% of the energy from the outgoing air supply. | Credit: Carol Laurie, U.S. Department of Energy Solar Decathlon

Good ventilation is vital for maintaining healthy indoor air quality. Houses built to modern energy efficiency standards, such as U.S. Department of Energy Solar Decathlon competition houses, are tightly constructed to allow very little outside air to leak in. As a result, odors, chemicals, particles, and humidity can become trapped, increasing indoor air pollution.

Energy-recovery ventilation systems provide tightly constructed houses with fresh air while minimizing energy loss. These systems rely on heat exchangers to efficiently transfer heat between indoor and outdoor air supplies. There are two types of energy-recovery ventilation systems: heat-recovery ventilators (HRVs) and energy-recovery (or enthalpy-recovery) ventilators (ERVs). An HRV uses fans to pull fresh air into a house while simultaneously exhausting stale air. In the winter, the heat exchanger transfers heat energy from the warmer outgoing air to the cooler incoming air to reduce the need for heating. In the summer, the system reduces the need to cool incoming fresh air by sending the cooler exhaust air past the warm intake stream. An ERV goes one step further by controlling indoor humidity as well as temperature. An ERV transfers water vapor along with heat energy to keep the interior humidity constant.

These ventilation systems can recover 70%–80% of the energy from a house’s outgoing air supply to help maintain a comfortable indoor environment.

Several Solar Decathlon 2013 teams incorporated energy recovery ventilation technologies into their competition houses. Norwich University provided continuous ventilation of its “Delta T-90” house by using a multiunit HRV system that was 92% efficient, ductless, and whisper-quiet. Team Ontario (Queen’s University, Carleton University, and Algonquin College), which received first place in the Solar Decathlon 2013 Engineering Contest, used an ERV in its “ECHO” house to dramatically reduce the energy needed to condition indoor air.

solar decathlon 2015

Norwich University used a multiunit HRV system that provided continuous ventilation in its Solar Decathlon 2013 “Delta T-90” house. | Credit: Jason Flakes | U.S. Department of Energy Solar Decathlon

Visit the Energy Savers website to learn more about energy-efficient ventilation systems.

Fans of the U.S. Department of Energy Solar Decathlon mark your calendars:

Solar Decathlon 2015 will be held October 8-18, 2015, at the Orange County Great Park in Irvine, California. You can check out the team lineup for the competition and the concepts for their net zero houses on the 2015 team pages.

Source: 1Sun4All. Reproduced with permission.

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About the Author

-- I am an artist, painter, writer, interior designer, and graphic designer, constant student of many studies and founder of 1Sun4All.com. Living with respect for the environment close at hand, the food chain, natural remedies for healing, the earth, people and animals is a life-long expression and commitment. As half of a home-building team, I helped design and build harmonious, sustainable and net-zero homes that incorporate clean air systems, passive and active solar energy as well as rainwater collection systems. Private aviation stirs a special appeal, I would love to fly in the solar airplane and install a wind turbine in my yard. I am a peace-loving, courageous soul, and I am passionate about contributing to the clean energy revolution.



  • Vensonata

    Hrv’s are essential in airtight houses such as passivhaus and many net zero houses. However they do require electricity. It is interesting that if one is off grid and supplying winter electricity through solar pv and batteries the hrv just takes too much electricity. The solution is a one way exhaust fan and slightly less than airtight house …still very efficient. Often wood heat is so cheap and a non contributor to green house gas because it is a closed loop surface plant carbon, that is cancels the energy and economic benefits which hrv have for grid tied houses.

    • Bob_Wallace

      Since I didn’t want to do a power air exchange (and wood is free for the cutting) I built my house well insulated but not super tight. The wood stove sucks in a bit of air and sends it up the chimney. Fresh air comes through the small ‘vents’ here and there.

      If I lived in a place with harsh winters then I might have made a different decision. A cold night here is in the upper 20s F. Usually hits 50F during the days.

      • vensonata

        I’m in about as cold as it gets winter conditions. 4300ft elevation 51 latitude north. The option for wood stoves (we run two of them in the day, and let them go out at night) is a direct feed air vent to the stove, or just a little screened opening in the wall which circulates fresh air until it goes in the stove and up the chimney. It all works. 10,000 sq ft house, six cords year, free wood all around, pine beetle killed.
        The Hrv off grid is a great debate subject that I’m still not decided on.

    • Offgridman

      The first year my woodstove got put in it was pulling cold drafts through the kitchen and bathroom vents. The following year set up six lengths of 4″ vent pipe six feet long behind it with double 90°’s connecting. One end draws in outside air, the other feeds it towards the wood stove draft at the bottom outlet. Homemade HRV with no fans that only pulls air when stove is burning. Third year put a draft plate on the outlet that helps to control the burn speed of the stove overnight, so I no longer have to get up in the middle of the night to feed it.

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