Somerville is a city northwest of Boston with a population of over 80,000 spread over roughly four square miles. It’s the most densely populated municipality in all of Massachusetts, and ranks 16th in the entire US in population density. My Alma Mater, Tufts University has its campus there on the Medford border–many good memories there.
Somerville has become one of the more trendy and desirable parts of the Greater Boston Area to call home–Somerville real estate values have risen 221% since the year 2000 and continue to rise. As of this writing, the average listing price for a home in Somerville is currently $920k with 179 homes for sale ranging from $250k to $4,500,000.
Somerville is also now beginning to lead by example in the creation of environmentally-friendly and energy-efficient Passive houses. Passive houses and their simplicity and importance are what I wish to table for consideration in this article. At NEDC, we are now helping a Somerville client retrofit an existing home to Passive house standards. This is a fascinating challenge and unique project which I hope many will emulate simply for the good it will do for the environment and planet as a whole.
The Passive house is moving increasingly to the forefront of cutting-edge environmental and eco design. Such are increasingly popular with professionals, families, and creatives who are environmentally aware and seek a home design which reflects their values through increased air quality, safety, energy efficiency and a reduced carbon footprint.
First of all–what is a Passive house in simple layman’s terms?
A Passive house is a simple concept which I’ve defined below and also is explained very well in this excellent and informative 90 second video:
Passive House Defined
“A building standard that is truly energy efficient, comfortable, affordable and ecological at the same time. Passive House is not a brand name, but a construction concept that can be applied by anyone and that has stood the test of practice.” (www.passipedia.org/basics/what_is_a_passive_house)
Passive House Origins
A Passive house is based on technology developed by an Austrian physicist by the name of Dr. Wolfgang Feist in 1991 after analyzing fossil-fuel use and discovering the largest share of fossil fuel energy consumption at the time (over one-third) was being used to heat buildings. Determined to find a more efficient solution that would foster planetary and environmental health over the coming decades, Dr. Feist pioneered the Passive house based on certain key design aspects.
A Passive house design has the following:
1. Proper external insulation for both heat and cold
2. No air leakages–no holes to permit hot air to escape from the home
3. No thermal bridges–meaning no conduits for heat to travel or escape through the walls
4. Properly insulated windows — usually triple-paned glass
5. A passive house is oriented so the sun can heat it in the winter and it is properly shaded in summer
6. A passive house uses an HRV (Heat Recovery Ventilation System), a device that provides fresh air without letting heat escape from the home
HRV defined simply:
“An HRV is a very energy efficient system that pulls the stale air from inside your home while simultaneously replacing it with fresh air from outside your home. An HRV works by drawing in the stale, warm air from inside your home along with the cooler, fresh air from outside your home. With these two separate airstreams in the system, they cross paths and a heat transfer occurs between them. Following the heat transfer, the stale air from inside your home is now cooler and is deposited outside. Meanwhile, the fresh air is now warmer and is supplied to the home. Through this transfer, there is no energy wasted and your home is kept comfortable.” (www.morrisonhomes.ca)
Now get this
A Passive home needs 90% less energy than a normal home and requires no heater or air-conditioner. Heat comes naturally from your body heat, the sun, appliances, and interior lights. This innovative design saves significantly on the heating bill and is far better for the environment.
That makes sense and honestly is amazing. This leads me to two main questions: are Passive homes prohibitively expensive to create? Is there an increased level of safety and comfort in a ‘normal’ home which is not built to Passive home standards?
These are fair questions which many homeowners will have when considering creating a Passive home either by new build or a retrofit of their existing home.
The Passive House International U.S. website (www.phius.org) sheds light on these two points as follows:
Passive Home Cost–is it more expensive?
“Currently, a Passive house typically costs about 5-10% more than a conventional home. Larger projects benefit from the economy of scale: a multifamily Passive building typically only costs 0-3% more than a building built to an energy star baseline. In general, the larger the building the less of a cost difference there is. Also, as more large-scale window and door manufacturers bring high-performance products to market, economies of scale are expected to drive down costs. “ (www.phius.org/what-is-passive-building/passive-house-faqs)
(Please note–this statement here on costing refers to new build–not a retrofit of an existing structure to Passive house standards)
Does a Passive Home provide an increased level of comfort & safety?
“Passive houses and buildings are extremely comfortable in all seasons. That’s because there are no drafts, temperature variance is extremely narrow (even near doors and windows), and active, balanced ventilation makes for superb indoor air quality. And yes, Passive house owners open their doors and windows just as they would in a conventional home.” (www.phius.org/what-is-passive-building/passive-house-faqs)
Interest in Passive home standards is increasing as concern for family health and safety has moved to the forefront throughout 2020, as well as a continually increasing concern for the environment and the planet’s wellbeing.
NEDC has taken on the unique challenge of retrofitting an existing home in Somerville, MA to Passive House International – US standards (PHIUS)–a feat usually reserved for new construction.
The clients sought a home as environmentally friendly and energy independent as possible and are working closely with NEDC to create this as we move through the design stage.
NEDC’s Senior Designer, Grady Ragsdale, is overseeing the project and shared the following:
“This project is an existing 2 ½ story, two dwelling structure, in Somerville, MA. The client wishes to convert the building back into single family residence for their own use and in doing so would like to take the opportunity to have the building constructed to Passive House International – US standards (PHIUS). The goal is to create a new home that is as energy independent as possible. By having the building designed and constructed through the PHIUS+ certification process, the house will achieve that goal. This project is unique as a PHIUS+ renovation since most certified structures are new construction. Working with existing structural components creates an interesting set of challenges. Although different than most PHIUS+ certified efforts, the growing trend in reducing energy consumption in the US and abroad will soon draw residential projects of all scope and scale into this important methodology.
PHIUS+ is a “high-performance building standard” – it challenges the building industry to construct buildings that can maintain a comfortable indoor environment with very low operating energy. Since the operating energy of a building over its lifetime far exceeds the embodied energy to construct the building, the PHIUS+ standard just focuses on reducing operating energy and does not specifically address the environmental impacts of the building materials and construction process. However, PHIUS+ is still compatible with other green building certification programs and broader sustainability concepts. PHIUS+ is a pass-fail standard for building energy performance, with additional requirements for quality assurance inspections, and for low-moisture-risk design.”
Grady Ragsdale’s architectural and building experience has been gained from over thirty years in the design and construction industry. He earned his architectural license in 1996 and is now registered in Massachusetts, Maine, and Pennsylvania. Over his professional career, Grady has worked on a variety of commercial and residential projects for offices located in Maine, New York City, Philadelphia, and Boston. The focus of his work has been in the single-family and multi-family residential markets, from public funded, affordable housing, to high-rise luxury condominiums. He recently completed his residence in Maine where he incorporated lessons learned to reduce the building’s energy use and carbon footprint.
All things considered, why would we not be working towards a world composed of Passive homes?
It bears strong consideration.