The Greenest House
What is the measure of true sustainability?
Some have said that the greenest house is the one that is already built. While in many cases this may be true, one could make a compelling argument that the greenest house is actually the one that is least likely to be torn down.
So what aesthetic and physical qualities should any house have in order to escape the sorry fate of a “teardown”? Likely, one or more of the following characteristics would need to be present:
- Enduring beauty
- Durability: Solid construction with exceptional resilience
- Functional adaptability to changing needs
- Healthy, quiet, light-filled interiors
- Draft-free thermal comfort, floor-to-ceiling, and floor-to-floor
- Low-load thermal performance
- Low operational costs with respect to energy and maintenance requirements
Interestingly, the sum of these qualities is arguably the measure of true sustainability. But before we tackle these attributes, one-by-one, let’s address upgrading the already-built house.
In general, retrofitting existing buildings for remedial performance issues can be a tricky endeavor, particularly if those problems are “baked in the cake.” Gaining access to the nether regions of an outdated house is not a simple process. Reverse engineering an older house in an effort to add insulation, eliminate thermal bridging, and improve airtightness enough to significantly raise its thermal performance (let alone reach today’s lofty, zero-energy-ready standard), is always a compromise, and an expensive one at that. Added to this, replacing old, poorly performing windows with today’s high-performing, double and triple-glazed versions is an expensive proposition.
Once the thermal envelope is addressed, the health of the indoor environment must be considered. The removal of unhealthy, high VOC (volatile, organic compounds) and other hazardous building materials that may be present is not always a financially viable option. Moreover, antiquated mechanical systems that have been cobbled together over decades, often don’t work efficiently in concert, and their replacement can be both structurally invasive and costly.
It is not surprising, therefore, that when the underlying value of an existing house is seriously compromised because its performance and health issues are “dyed in the wool,” the cost/benefit analysis of retrofitting, at least in the name of “sustainability,” can sometimes come up wanting.
As such, when tearing down a home is determined to be the most sustainable option—both financially and environmentally—the house cannot be considered “greenest” simply because it already exists.
What Makes a Green Home?
Beauty is a vitally important to sustainability. First and foremost, for a house to be saved over generations, it must be loved over generations. And while “beauty is in the eye of the beholder,” the timeless, honest paradigm of “form following function” holds true for classical, contemporary, and ultra-modern architectural styles alike. Instinctively, we seem to hold this design aesthetic to be self-evident, so preeminent architects lead with this time-honored credo as they strive to realize client tastes and objectives.
Durability is an essential component of sustainability. Houses should not be considered disposable. The energy and material that goes into building a house comes at a serious cost to our bank accounts and to our environment. Houses, therefore, should be built to last for centuries. Robust wood houses sequester carbon over their life spans, which means they assist in forestalling climate change while helping to weather its worst effects. Beyond this, solidly built, resilient homes can offer a palpable sense of security, and well-being.
Functional Adaptability allows homes to adapt to our changing needs over time. No one can predict what those future needs will be, but Open-Building protocols permit simple changes to a home’s functionality, without the necessity for demolition and reconstruction involving multiple trades and overburdened landfills.
Healthy, quiet, light-filled, interiors are instrumental to biophilic design, helping us to connect with nature. The human affinity for natural materials like wood and outdoor views of nature’s rhythms, promote mental and physical health in ways that are just beginning to be fully understood. Moreover, solid, sound-dampening, wood construction helps to mitigate both external and internal noise pollution.
Draft-free thermal comfort in low-load, well-insulated, airtight houses, comes from their extremely low-temperature differentials, floor-to-ceiling, and floor-to-floor. This eliminates the need for registers in every room (and their related ductwork), allowing for fewer, combustion-free, point source heating systems, like air source heat pump systems, for heating and cooling. Finally, air quality is maintained using heat recovery ventilation systems (HRVs) or energy recovery ventilation systems (ERVs) that condition incoming air with exhausted air, resulting in fresh air with minimal energy loss.
Low load thermal performance means that small HVAC systems powered by renewable energy are all that’s needed for zero-energy performance. And as an added benefit, the need for fossil fuels to condition a home can be all but eliminated.
Low operational costs are critical to both our personal finances and our environmental footprint. Poorly insulated, drafty houses, requiring massive amounts of fuel to heat and cool, cannot survive long in a world of limited resources and carbon-based, atmospheric pollution. Conversely, highly-insulated, tightly-sealed houses with small, sophisticated HVAC systems can sip rather than gulp fuel, to the point where inexpensive, clean energy generated from the sun or the wind is sufficient for thermal comfort. Beyond energy costs, robust, resilient construction and Open-Building protocols that permit simple modifications, can significantly reduce maintenance expenditures, year-after-year.
So what is the “greenest” house in terms of sustainability? It’s a multi-faceted issue, as outlined above, and there are many exceptions.
With the approximately 74 million existing, occupied, single-family, detached houses in the U.S.*, even incremental improvements in their performance can and should play a key role in promoting health and curbing greenhouse gasses. Retrofitting existing homes cannot be considered an all-or-none proposition. The battle for sustainable living will need to be fought on all fronts.
Beyond this, if a house is historically significant, its cultural importance may trump its sustainability. “Cultural sustainability,” if you will, is also critical to society, offering a continuity of past, present, and future. In this vein, however, it’s important to note that today’s super-sustainable buildings can become tomorrow’s historically significant structures by virtue of their high-performance design attributes alone.
Ultimately, taking the long view is what true sustainability is all about. Crafting new homes that are worth saving is key. To that end, we can build our way to a “greener” future.
*As measured in 2014 by the U.S. Census Bureau. The 74 million figure is tabulated from the 2014 ACS (American Community Survey) PUMS (Public Use Microdata Sample) from the US Census Bureau.