Net Zero Cities: Reinventing existing buildings presents challenges, opportunities

LOVELAND — Operations of existing buildings account for 28% of carbon emissions, with building materials and construction accounting for another 11%.

Those statistics heighten the importance of reconfiguring existing buildings in order to address climate change, Paul Kriescher, senior consultant with Bowman Consulting, said at BizWest’s Net Zero Cities event in Loveland Wednesday.

Kriescher moderated a panel titled “Reinventing Existing Buildings.” Panelists included Jeff Hindman, founder and owner of Cottonwood Builders; Christine Brinker, senior buildings policy manager for the Southwest Energy Efficiency Project; Anna Perks, owner of Perks Deconstruction Ltd.; and Bill Lucas-Brown, co-founder and vice president of Net Zero Solutions.

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“Twenty-eight percent of emissions are coming from the operation of buildings here in the United States,” Kriescher said. “It’s such a huge part of this equation … There can be so much done on the existing-building side.”

Hindman agreed, saying that many existing buildings can be brought up to the same energy-efficiency standards as new construction.

“If we’re going to attack climate change, we need to attack it from all angles,” Hindman said.

He said the majority of new buildings, including production homes, are performing at a “reasonably high level” in terms of energy efficiency, and “Getting the majority of the existing buildings up to that same standard is critical if we’re going to fight climate change.”

Kriescher said that property owners should begin to address carbon emissions by securing an energy audit of their property, which would provide a ranked, prioritized list of improvements to implement, such as addressing insulation, air leakiness, windows and lighting.

Lucas-Brown noted that different types of audits can be conducted, depending on the needs and desires of the property owner.

“What are we looking for?” he asked. “You can have different audits. Is it for comfort because I’m going to look for something very differently in a house if I’m looking for comfort issues, which, if it’s a new home, you don’t know. Is it for air quality? Then I might be looking at filtration, pollution sources and air-leakage sites. Is it for efficiency? I’m looking at the windows, again, air leakage. I’m looking for insulation.”

Lucas-Brown said that Xcel Energy will conduct energy audits for a couple hundred dollars, with rebates available for some improvements.

But he cautioned that buildings must be looked at as entire systems. Some contractors might address one problem and exacerbate another, he said. An example would be a hot-water heater that wasn’t venting properly, with an anemic draft. If a contractor performs air-sealing work on the home, that problem might be made worse, he said.

“That’s not what we’re about,” he said. “Like the medical profession, do no harm. That’s got to be one of the major tenets.”

Improvements to energy efficiency run the gamut from sealing air leaks to improved insulation and mechanical systems, Hindman said. One option would be to install heat pumps instead of a fossil-fuel furnace. Electric heat pumps are energy-efficient alternatives to fossil-fuel-powered furnaces.

“It really is a continuum,” Hindman said of the range of improvements that are possible. “The most important thing and the most common problem with an existing building is the envelope.”

Brinker, who has worked on energy efficiency for her own home, said that technologies such as heat pumps have improved markedly in recent years but that some contractors remain reluctant to embrace them, even as costs for new technologies come down.

“We were mentioning that costs are getting to be nearly comparable, but I don’t think that’s translated yet to all the installers. The costs were all over the board, which speaks to the importance of getting more multiple bids. I think some contractors are just more used to how they have done things in the past and so are more uncomfortable with the newer technology and thus maybe needed to add extra padding to the cost to cover some of those uncertainties.”

Additionally, some contractors insisted on having natural-gas backups for heat pumps, “which I think is more of a personal choice than a technology choice,” she said. “I don’t think you need gas backup in the metro area, certainly depending on which heat pump you get.”

Perks, whose company handles deconstruction of buildings, said recycling or donating waste from demolition projects can help divert substantial waste from landfills.

“It involves taking that surgical approach to demolition to maximize the salvage and reuse value of the material,” she said. “So, essentially, we approach every job with a salvage-first mentality.”

Perks said she begins projects by talking with the client about the scope of work and creating a waste-management plan to identify what can be donated to a nonprofit and what can be recycled.

“If it’s not recycled, then the last option would be landfill,” she said, noting that 40% of a typical landfill is construction and demolition debris.

Diverting that waste remains a top priority.

“When we deconstruct full houses, we aim to divert at least 75% of the house from the landfill,” she said, reusing material such as lumber, plywood and insulation when possible and donating or recycling appliances.