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Building Decarbonization: What’s Next and What Can Engineers Do

Building Decarbonization: What’s Next and What Can Engineers Do

From ASHRAE Journal Newsletter, Oct. 26, 2021 

Changing how buildings are designed, constructed and operated is a challenge. As more cities, states and companies declare their intent to transition to carbon-free electricity and clean energy, the HVAC&R industry is looking for ways to decarbonize buildings, which means changing design, construction and operations processes.

“New construction is still natural gas-powered. It's oftentimes hard to change how we build buildings to a new way of doing it,” said Peter Rumsey, P.E., Fellow ASHRAE.

Structural engineers are used to boilers being a certain size and weight; contractors are used to installing boilers in certain places. But boilers are not being installed in buildings that are designed to be all-electric. Instead, heat pumps and other technologies are. That learning curve is a challenge.

“Full decarbonization is now possible. We can change out our natural gas burning heating systems, hot water systems, cooking systems to efficient electric alternatives. And we can now connect buildings to renewably generated electricity,” said Rumsey.

Talking Options

One way to ease the transition and the learning curve is to give clients and tenants options, said Rumsey.

He recommended HVAC designers talk to their suppliers and see what equipment is available. From there, design and price out all-electric and natural gas-powered systems for a project. Having both plans designed and priced helps HVAC designers discuss decarbonization and options with owners.

Rumsey recently worked with a developer in Alameda, Calif., and was able to help his client choose an all-electric, decarbonized option. Rumsey said he was able to make the case that a variable refrigerant flow (VRF) would be a more affordable option than a gas boiler heating system.

“Both the developer and the tenant agreed. Making the move to a 100% electric building was simple from there,” he said. “The savings of eliminating the gas infrastructure for just the water heating and full cafeteria lowered costs and simplified the construction.”

The tenant wanted to make a statement of environmental responsibility to its employees, so they also put as many solar panels in the parking lot and on the roof as possible, according to Rumsey.

“But these panels only cover half of the building’s energy use. Luckily, the utility serving the building provides electricity from 100% renewable energy generation. In combination with the all-electric design, the building has fully decarbonized operation,” he said, adding that this could be a model for future new construction buildings where renewables are a growing fraction of electricity supply.

Renovating Existing Buildings

Adopting and implementing technologies to decarbonize buildings will be challenging, especially in existing buildings.

"I think one of the barriers would be existing buildings are going to be a little tricky to retrofit for electric because they've been set up for some gas and some electric, and now we're saying all electric,” he said. “I've started to work on existing buildings and retrofitting existing buildings, and I've found that, in most cases, we can electrify and fully transition over to heat pumps within the constraints of the existing electrical service.”

Rumsey said he is currently part of the design team working on the American Institute of Architects’ (AIA) headquarters renovation in Washington, D.C.

“The building built in the 1970s is a typical office building from that era that leaks energy and depends heavily on large gas-powered steam boilers,” he said.

Rumsey’s approach to this project is to transition the building away from gas to heat pump heating systems.

“New heat pumps will be placed on the roof and feed hot water to new coils in the air handlers and perimeter heating system. The utility in Washington, D.C., has a community choice aggregation (CCA) option where customers can select their generation provider. For a small increase in utility rates, the AIA will be able to purchase 100% renewable electricity generation sources,” he said.

CCA schemes are available in seven states, with more expected to come. “While some states have targets of getting to zero carbon electricity by 2050, utility customers in the CCA areas can choose zero carbon electricity today. The more customers that select these options, the faster the transition,” he said.

Rumsey said he also helped devise a scheme to offset the “embodied” carbon of the building renovation by having the AIA purchase a solar photovoltaic (PV) system for a local school. He hopes the AIA project will be a model for simple ways to decarbonize the large stock of existing buildings.

Looking Ahead

As the HVAC&R industry and the built environment move toward a low-carbon future, there are various ways to overcome these barriers. In the past, green building strategies and rating systems, education and standards have helped move technology forward, he said.

“As the market grows for this equipment, the contractors will start to get comfortable with it. The prices will start to come down; the reliability will improve all these things,” he said.

Rumsey added building codes, such as ANSI/ASHRAE/IES Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, could also be vehicles to motivate widespread adoption of building electrification and decarbonization.