At some point in the decision to buy a home, there comes a critical calculation: Do I build a new house on my own land, or buy an existing one? And if that existing home is poorly constructed or simply outdated, how will that impact me over time?
Aside from the obvious fact that existing buildings are where they are, as opposed to where you’d like them to be, they also come with hidden costs that may not be immediately apparent to the average homebuyer. As one example, getting older existing houses up to current energy code, let alone the stringent standards of today’s high-performance buildings, can involve impossibly long payback periods.
Martin Holladay, in writing for Green Building Advisor, indirectly addressed this issue in his March 2014 article, The High Cost of Deep-Energy Retrofits. In the article, he asks the question, “How much does it cost to perform a deep-energy retrofit on a 100-year-old single-family home?”
His findings? Around $100,000.
Mr. Holladay based his finding on a study that was sponsored by the New York State Energy Research and Development Authority (NYSERDA). The program, centered in the Utica, New York area, paid for deep-energy retrofits of four wood-framed buildings.
So, how were the “deep energy retrofits” defined? In a nutshell, the goal was to reduce energy use by 75% by insulating slab floors to R-10, below grade walls to R-20, above-grade walls to at least R-40, upgrading windows by adding either low-e storm windows or new windows to achieve a U-factor of 0.25, achieving an airtightness goal of 0.15 cfm @ 50 pascals per square foot of surface area, and updating to the latest HVAC systems.
Without going into the myriad steps required to achieve the above, the retrofits resulted in impressive levels of energy reduction. Though the goal of a 75% reduction was not met, overall energy usage was reduced by 60-65%. But while the retrofits resulted in draft-free comfort with new siding, windows, and HVAC systems, the energy savings alone, in Mr. Holladay’s words, “…can’t possible justify the very high costs of this type of retrofit.”
In fact, when factoring in the retrofitting costs to the energy savings, at least on houses built in the early 20th century, the study found that the simple payback period was 139 years, longer than the houses were old!
So, getting back to the original question, how does the green home buyer evaluate building new vs. retrofitting an existing building? It’s a complex subject with many variables, but what becomes immediately apparent is that it can be easier, more efficient, and in some cases, less expensive to build your high-performance home from scratch than to retrofit an existing older home.
That’s not to say that existing homes shouldn’t be updated to improve their performance. There are many who feel that the greenest building is the one that is already built. Some buildings are indeed worth the investment because of the inherent quality and craftsmanship in their original construction. Moreover, with historical and rare buildings, even condition is relative and preservation may trump energy performance.
But some buildings are clearly not worth it for the opposite reason. The embodied energy in an existing building is only part of the energy equation. Operational requirements, especially involving fossil fuels, affect the true cost to the owner as well as the environment. Every energy retrofit should begin with that calculation. Better technology and systems for economically achieving deep energy retrofits need to be developed with an eye towards getting the cost down. There are some very interesting scanning technologies available today that just may be a way to get there.
It’s important to note, however, that most of the homes needed in the next 50 years (because of population growth and demise of existing stock) are yet to be built. The next generation home HAS to be much better in every respect, but especially in the elimination of fossil fuel dependence. Thankfully, the technology and systems for building sustainable, healthy, Net Zero-ready homes (with Passive House levels of air tightness) are available today.
Either way, to achieve the aggressive environmental goals the U.S. has set for the coming decades, all buildings (which account for over 40% of total US energy consumption) will need to do their part in forestalling climate change.