Heat pumps aren’t the answer to everything, but you wouldn’t know that by the amount of chatter and money dedicated to the topic.
The truth is heat pumps are only a partial solution.

Even when the envelope is acknowledged as a part of the equation for improving efficiency, most of the time the solution plugged in is additional insulation. The arguments made in favor of this approach, especially in retrofits, is that improving the insulation of a building’s envelope is less expensive and less disruptive than replacing windows.

In my last blog post, links to resources mentioned at the National Fenestration Rating Council’s (NFRC) Fall Meeting were included but not discussed. It’s time to discuss them and hopefully prompt all of us to take the necessary steps to counter the conventional “wisdom” that favors insulation over windows.

In a short video by Acelab, a registered provider of American Institute of Architects (AIA) continuing education, presenter Christine Williamson, director of building science and education, discusses “Why Glazing Matters So Much More Than Insulation.” Using several examples, she demonstrates how improving the insulation in a building makes very little difference in total thermal performance if the windows aren’t addressed. By improving the efficiency of the window, the overall thermal performance of the wall is significantly improved. The video is well worth watching (and it is less than 10 minutes in length).

The second reference provided by Rick Dunn, now senior manager, emerging technology with CalMTA, is a pamphlet (Triple-Pane Windows with a U-Factor of 0.22: A Better Builder Value?) including information on a case study from Oregon. Counter to the belief that insulation is more effective and less costly than triple-pane energy efficient windows, the case showed that “when comparing available options, high-performance triple-pane windows fit the bill, adding approximately $700 per unit to the bottom line as opposed to 1-inch rigid foam insulation, which would have added approximately $5,000 per unit—to achieve the same level of energy efficiency.”

Grace Weger, director of land acquisition and development for Habitat for Humanity, noted that “… a lot of builders don’t know triple-pane windows can be affordable. Even our builder who has been in the industry for more than 40 years was astonished.” (Side note: the buildings in this case study have since won two Earth Advantage Awards – Most Net Zero Homes and Project of the Year: Affordable Single Family. More information here.)

About a year ago, a study in Environmental Science & Technology showed that replacing coal stoves in homes in rural China with clean heaters did not lower heating demand as much as expected because the building envelope efficiency wasn’t properly addressed. In rural areas of China, most homes are built by the residents out of solid clay brick, aren’t insulated, and windows are single-pane and poorly sealed. Based on this, it is no wonder that changing heat source—but nothing else—proved ineffective at lowering power demand, though removing coal burning sources did improve air quality. The study’s authors note that had the entire building envelope been considered and addressed, including new efficient windows, the heaters provided could have been smaller and required less energy to run.

Though this study looked specifically at homes in China, the findings apply globally. Note the authors, “policies that encourage improvements in building envelopes [efficient windows included] as well as the uptake of clean and efficient heaters are critical.”

So how does the fenestration industry gain equal consideration in the heat pump discussion? Are there missed funding opportunities for manufacturing that would lower costs for consumers?

First, we work on research. Categorically demonstrating how high-performing products reduce energy use is critical to counter what people believe to be true. In addition, it’s not just having the research, we must share it – with each other, by educating consumers, with allied industries, with policymakers, and with those who disagree.

Second, we need to be louder and on the same page. NFRC and the industry associations have data that can be used to educate and convince. For example, in its 35-year history, NFRC’s certification standards and data have allowed inclusion of fenestration in Energy Star, codes, and are trusted such that the label is evidence for rebates and tax credits. This is just a beginning and there is room to grow, particularly in the commercial sector.

We can also build and improve on our partnerships with allied organizations and those who are committed to better buildings. Working with others with a shared goal, we can help educate outside our individual networks to demonstrate how efficient fenestration products are a crucial component of the whole build.

Each organization, manufacturer and ally has a purpose and a strength that can be harnessed to get fenestration recognized in these winning formulas. As a 501(c)3 organization, NFRC provides unbiased thermal performance ratings and educates the public on how energy efficient products can influence their energy consumption and comfort. We are also able to provide educational and research information that other organizations can use to influence policy.

Let’s be in this together.

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