The Harvard Center for Green Buildings and Cities is renovating its headquarters, a 1924 historic home in Cambridge, MA, into “HouseZero,” a project designed to demonstrate that energy efficiency can be implemented in existing homes, Metro reported. The project team includes Snohetta, Skanska Teknikk, Skanska USA and Columbia Construction.
Changes include eliminating the HVAC system for a thermal mass to absorb and store heat as well as a ground-source heat pump; an automated system will use algorithms to open and close windows. The house also will incorporate daylight-enhancing features to eliminate the need for electric lighting during the day.
Once complete, the building will collect data for use in the development of new energy-efficient technologies. Other features include a solar vent and triple-glazed windows oriented for cross-ventilation.
Buildings account for 41% of energy used in the U.S., according to the International Energy Agency. Of that figure, the residential sector takes the largest share, ahead of commercial and industrial buildings, respectively. Within buildings overall, features such as space heating, air conditioning, illumination, water heating and refrigeration lead energy consumption.
In homes, specifically, 42% of energy use comes from space heating, followed by appliances and electronics (30%), water heating (18%) and air conditioning (6%), per the U.S. Energy Information Administration.
While low-energy features can readily be incorporated into new homes during design and construction, upgrading existing homes is more of a challenge. What’s more, older properties account for a significant share of existing homes today.
As of 2013, roughly two-thirds of owned existing homes were built before 1980, with 40% built before 1970, according to the National Association of Home Builders. That means most homes in the country lack the energy-efficient design features that form even the baseline of homes built today.
In a recent study by The Farnsworth Group, 33.8% of remodelers reported that they are seeing revenue growth in work related to energy efficiency, second only to aging-in-place renovations.
Some energy-efficiency updates go beyond swapping in more efficient windows or upgrading appliances for greener options. A deep energy retrofit that addresses how a home uses energy can result in energy-use savings of 50% to 90%, according to Regreen, a partnership between the U.S. Green Building Council and the American Society of Interior Designers Foundation that offers guidance for energy-efficient residential remodels.
Among other projects with a similar aim to Harvard’s is a deep energy retrofit conducted on a 1910 Portland, OR, home by the Department of Energy, completed in November 2011. Outfitted with a more robust envelope, including insulation and air sealing, and as well as a new, efficient HVAC system, the home was brought down to a HERS rating of 68.