The decarbonization of buildings is no longer an aspirational idea. The biggest cities and most progressive states in America, and in the world, have begun to finalize concrete plans to phase out fossil fuels in building systems and on the electricity grid. 

The public is increasingly bemused by the notion that the construction industry or any part of the private sector will clean things up themselves without regulation to create the necessary imperative — and a level playing field. Most of the changes to building requirements are starting in the larger cities, while states are taking the lead on the transformation of our power system. 

According to the Sierra Club, Atlanta, Chicago, Denver, Los Angeles, San Francisco, St. Louis and 127 other U.S. cities and 11 U.S. counties are committed to 100-percent renewable energy. In Canada, Toronto, Vancouver, Montreal and a handful of other Canadian cities have set goals. These governments announced objectives and deadlines to achieve the use of 100-percent renewables a few decades out. They are following up these proclamations with specific programs to hit the targets in a phased way. 

Some smaller towns already have achieved 100-percent renewable power generation. Others have found it easier to get there than they thought and have accelerated their schedules. I haven’t heard of any that have done the opposite.

California, the District of Columbia, Hawaii, Illinois, Maine, Massachusetts, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, North Carolina, Pennsylvania, Puerto Rico, Washington and others have already enacted, or soon will pass, similar legislation at the state level.

Power generation isn’t complicated because it involves proven technologies that now cost less than coal and gas: wind, solar, hydro, electricity storage and load management software. 

Buildings are more difficult. Still, Boston, New York, LA, San Francisco, Seattle, Toronto and Vancouver have already created phased-in but demanding decarbonization requirements for buildings. Numerous other cities will soon do the same. For example, Chicago has committed to 100-percent renewables for the city as a whole as well as its city-owned buildings. It is now working on details for private sector new construction and retrofits.

There has been a lot of chicanery in all these jurisdictions with gas companies fighting to mangle incentive programs so they don’t permit fuel switching or power utilities levying heavy fees on solar rooftop arrays. Most of this is becoming old news. 

It’s difficult to ignore that the Amazon, Alaska, Siberia and the Arctic are all on fire like California, the Midwest lost most of its agriculture season to several feet of floodwater, equatorial countries will soon be unlivable due to heat waves and lack of water for drinking and growing, the ice at the north and south poles and on Greenland is melting at astounding rates, and Miami, New Orleans and numerous other coastal cities may soon find themselves permanently encroached by seawater. 

One of the architects I talked with recently estimates that in New York City, about 36 million tons of CO2 are emitted each year just to power buildings.

Most of the mechanical professionals in the country are already working with low-carbon systems, but if you aren’t, the time to start is now. Do a little research to identify the most proven technology and start using some of it on projects. Partner with engineers who already have experience or recruit some sharp young talent who can help out. 

Beef up training and professional development for everyone on your team in low-carbon systems such as air-source heat pumps, ground-source systems and passive house construction. One of the first things you’ll learn is the mechanical systems of the future cannot be created without consideration of what other building elements are involved and what other trades are planning. 

Modern electrified systems are electronically sophisticated, based on refrigeration principles, and precisely and holistically right-sized for tighter building envelopes, solar gain and so on.

Passive House at Cornell University

The House at Cornell Tech appears to be an average 26-story, high-rise student residence in the middle of Roosevelt Island. On the outside, it’s not all that architecturally striking; inside, it’s attractive, well-designed and offers numerous amenities for students and faculty. 

One of the reasons this new building seems like an ordinary square box is because it’s built to the passive house standard. That means heavy insulation as well as minimizing thermal bridges, perforations and other threats to the control of energy leakage. 

It means that building envelope integrity and eliminating carbon affect numerous other design and construction decisions, such as the size and quality of the windows, the decision to employ some factory-made pre-fab components from Pennsylvania, and the use of VRF heat pumps and energy recovery ventilators (ERVs). The big glass boxes architects have been creating in cities don’t usually work for passive house. Cornell’s total glazing is 23 percent of the wall area.

Is passive house just a nice label for cocktail party conversations? Is it similar to LEED or other certifications? Yes, a little, but mostly no. Lois Arena, director of Passive House Services at New York City-based consultant Steven Winter Associates Inc., says the Cornell project saves 80 percent to 90 percent on heating costs and heat-related pollution. It saves 30 percent to 50 percent on cooling costs. And it saves 60 percent to 70 percent on whole-building energy. 

These savings are not just nice-to-haves. A passive house building must meet measured outcomes. With LEED, you can get to silver status and still use gas boilers. The primary conditioning system of a passive house building cannot use fossil fuels. You can’t get certification without actual, measured results.

“[The House at Cornell Tech has] a VRF condenser on each floor, and they are zoned north and south,” Arena explained. “One condenser would do two floors north, one would do two on the south side, and so on. Every of the 352 apartment suites has a floor-mounted evaporator unit fan coil (at the perimeters), which are probably not used in shoulder seasons because they’re not needed. 

Arena added that each apartment has its own thermostat because it’s an international group living there. 

“Some come from Holland, some grew up in Zimbabwe, so they all have different temperature sensitivities,” Arena said.

Three rooftop ERVs provide fresh, dry, temperate air while retaining the heating or cooling energy from combination kitchen/bathroom exhaust fans. In the shoulder seasons, the building needs little additional conditioning beyond these ERVs because of reduced loads and the integrity of the building envelope.

The 9-foot by 36-foot prefab insulated passive house wall sections of The House at Cornell Tech are about 1-foot thick. They arrived on trucks and were craned quickly into place, with triple-pane windows and doors already sealed into them. Prefab panels improve envelope quality while saving labor, and changes the construction schedule from a linear exercise to a parallel effort.

“This building was designed about five years ago; at that time, everyone assumed a passive house [design] would cost 5-percent to 7-percent more,” said Deborah Moelis, principal at Handel Architects, also based in New York City, which designed The House at Cornell. “Since then our firm has been involved with many passive house projects and it’s now more like a 1-percent to 4-percent [cost difference].”

Moelis says the design firm recently priced a conventional four-pipe fan coil versus a variable refrigerant flow (VRF) system for a nine-story building. 

“The VRF was cheaper and more efficient because, with the four-pipe fan coil, you have miles of piping and pumping,” Moelis explained. 

Although others have become confirmed prefab panel fans, Handel projects are just as often stick-built on-site. 

“We sometimes grapple with the best façade approach,” Moelis said. “There are regions and reasons for using the prefab, but it can be tough in tight places such as New York City. And those cranes cost so much money. It’s crazy.”

As one of the first architect firms in the New York area to develop passive house expertise, Handel is now working on numerous projects, including a 709-unit affordable housing complex in Harlem called Sandero Verdes and the Winthrop Center, a 750,000-square-foot office building complex in Boston. 

“We already had 25 years of experience with multifamily projects and then we were fortunate to work on these modern buildings,” Moelis said. “Now I think anyone with a multifamily passive house project in the New York area would give us a call.”

Moelis noted that with the move to more energy efficiency in the U.S. energy codes, the step toward passive house is obvious. 

“It’s fairly unknown now, but it won’t be unique in 10 years,” Moelis explained. “I go to conferences and hear developers say ‘I have no idea what you’re talking about, so I’m passing on this.’ There’s just a lot of education needed. It’s similar to the early days of LEED when people felt overwhelmed by the paperwork and the cost. But today if you’re not at least LEED Silver, you’re subhuman. With passive house, we’re reclaiming attention to detail. The goal is to build a better building and that’s what this is.”

Alabama Solar Microgrid

In some places, the goal is to build a smarter, futuristic subdivision of detached houses. At Reynolds Landing in southwest Birmingham, Ala., this has been done by Alabama Power in partnership with the Electric Power Research Institute, the Oak Ridge National Laboratory, developer Signature Homes and equipment vendors such as Carrier, Rheem and Vivint. 

The project started with the group wanting to learn more about what happens in real life when you install the newest low-carbon and smart-home equipment into 62 single-family homes — as well as create a solar-and-battery microgrid to power the whole neighborhood. But it ended up as something more. 

Signature sold the homes in record time, discovered a new homebuyer conversation based on value and initiated several similar new projects because it’s good business. The future has already arrived in Alabama.

The project did not seek passive house certification but it shared many of its characteristics, including a superior thermal envelope, smart thermostats, air-source heat pumps for space conditioning, ERVs and heat-pump water heaters. 

Homeowners signed up for two years of data collection as well as some demand response by the power company. The goal was to make detached homes 35-percent more efficient, but the actual numbers hit around 44-percent more efficient. This achievement makes the solar microgrid economically viable, which, in turn, delivers a near-zero operational carbon footprint.

Energy-Efficient Affordable Housing in Portland

When you clean up power systems, electrify buildings and reduce your carbon footprint, you generally save on operation costs, too. The Orchards of Orenco Phase One in Hillsboro, Ore., a 57-unit affordable housing project built in 2015 to the passive house standard, is achieving the goal of making life more affordable. 

“Through the [building] envelope, triple-pane windows and other methods, we are able to get utility bills down to a total of $20 to $30 per month for tenants,” said Ben Sturz, housing project development manager at Reach Community Development in Portland. 

“With the age of climate change that we live in, [energy efficiency is] important on many levels, not just environmental impact and carbon footprint,” Sturz added. “Carbon efficiency is a way to bring down the cost of living for people, especially people of modest means. Doing an efficient project is meaningful.”

The Orchards is Passive House-certified, employs some centralized ERVs in rooftop penthouses and electric cove heaters in the units. In the Portland climate, cooling is not a significant factor. The design included plenty of operable windows, which can be opened as needed by staff and tenants.

Low-Carbon Multifamily in Boston

It’s not surprising that low-carbon equipment works well in buildings in temperate climates such as Portland, but the modern systems also work in New York, as mentioned, in numerous locations in frigid Canada and legendarily brutal Boston. 

Air-source heat pumps have been redesigned in recent years to perform well during cold winters; however, an active thermal building envelope is a crucial part of that equation. It’s probably easier to design modern electrified buildings from scratch as new builds, but retrofits are beginning to pop up, too.

As reported in this space last year, an old factory building in Boston was rehabbed into an affordable multifamily passive house project. The Distillery North Apartments have thick walls, triple-pane windows, solar photovoltaic panels on the roof and a P-Series Mitsubishi air-source heat pump in each unit, along with a dedicated thermostat and a heat recovery ventilator.

Sarah Carter, a project manager at Petersen Engineering in Portsmouth, N.H., noted that a passive house building significantly reduces the loads and much of today’s HVAC equipment offered in preset sizes would be oversized, especially for one-bedroom and two-bedroom apartments.

When Petersen started this project, it planned for a two-year test in just a few apartments with small systems and better insulation. It was immediately successful and Petersen’s team completed the whole-building retrofit ahead of schedule. Thanks to the solar panels on the roof, the building envelope and minimized mechanicals, residents pay about $65 each year for heating and cooling.

With emission levels that meet the increasingly demanding targets of local governments, and cost and health benefits for users, many of tomorrow’s buildings are likely to be designed with precisely sized mechanicals and integration with other building and clean energy systems. Even heavier base loads may go green via ground-source heat pumps or similar technologies. 

This is all basically refrigeration-based equipment and not a big leap for any mechanical professionals who have not yet tried it. 

Some people think if they ignore it, our climate crisis will go away. I wish I could agree, but I don’t. And it appears our regulators don’t either and are determined to eliminate gas-fueled appliances in the next 5 to 15 years. If you’re not prepared for the shift, it might be time to think about it.