Funded by an "Energy in the Environment and Recycling Technology" grant by the Pennsylvania Energy Office, the Greenhouse Bioregenerative Air Purification System began in fall 1991. They system consisted of various student-built components wherein the interior air of the Harmony Homestead will be interfaced with the leaf and root systems of specifically chosen plants in the attached greenhouse. Plants will be chosen for their ability to remove common interior air pollutants in energy efficient homes. Source: Ron Gargasz, Alternator Article, September/October 1991.
    In 1994, MS3 graduate, Mark Licklider, developed a plan to continue research on the Harmony House green lung system. Licklider insulated and sealed off a crawl space adjacent to the greenhouse as per the original design of the building. This effort helped to seal off an energy sink and ultimately improve the air quality of the house.
    The maintenance of good indoor air quality (especially during winter when doors and windows are closed) is accomplished in a variety of ways. For instance, the use of passive solar, photovoltaics, and fluid filled base board heaters means there is no indoor internal combustion. Internal combustion, whether of wood, natural gas or some oil-based derivative, can contribute to indoor air pollution. At the same time, use of interior plywood, particle board, or wafer board is avoided as such materials can out-gas toxic fumes such as formaldehyde. The superior choice, from the nontoxic standpoint, is to use hardwood instead. The Harmony House has hardwood cabinets and hardwood floors throughout.
    Also in 1994 as a follow-up, MS3 student Steve Hammerstone is evaluating the indoor air quality at the Harmony Homestead. The results of which are being kept on file as a record of the green lung's effectiveness. - Source: Alternator Article, May/June 1994