William Maclay

“Net Zero communities” is a new term for something as old as human history, and also the pathway to a renewable-powered planet, according to US architect William Maclay, whose Vermont-based practice in the US  specialises in sustainable design.

Maclay’s recently released book, The New Net Zero: Leading-Edge Design and Construction of Homes and Buildings for a Renewable Energy Future, brings together lessons learned in over 40 years of designing Net Zero-ready biophilic buildings and puts them in the broader context of the history of energy use and current global trends in sustainable design, construction and energy systems.

Stone House – a Net Zero home using local stone       photo courtesy Carolyn Bates
Stone House – a Net Zero home using local stone photo courtesy Carolyn Bates

“We’re at a turning point in history like that of the Renaissance moving from the mechanical world view to the biological one,” Maclay told The Fifth Estate during a phone interview.

“Net Zero is a component of that.”

His definition of Net Zero is simple – “buildings that produce through renewable sources more energy than they consume”.

The book details a wide range of ways this can be achieved, including case studies of buildings that use renewable energy and the ways in which any building, new or existing, can become Net Zero through improving energy and thermal efficiency first, then meeting the balance of energy required through renewables.

This includes on-building systems, on-site systems, and accessing energy from off-site installations, including neighbourhood-based energy generation.


Having spent his entire career examining the relationship between energy, buildings and the users of buildings, Maclay reflects on how different energy sources shape communities.

“The source of energy of a society determines what we are doing more than people think,” he says.

“Oil makes it easy to drive in cars, and led to the creation of the suburbs. It’s important in terms of laying the ground work [for Net Zero] to understand that.”

Maclay says that the mechanistic worldview that arose in response to thinkers such as Newton and Descartes has led to an “incredible level of innovation”, but at the price of our connection to nature itself.

“For millions of years we were connected to nature,” he says.

His point is that fossil fuel use is “not a part of who we are”.

“Humans have lived in Net Zero societies throughout history with an aberration of 100 years. [Our ancestors] were not powered by fossils.”

One of the striking things about his book is the combination of deep thinking on biophilic design, energy, society, beauty and human nature, with absolutely practical content on how to design and build for Net Zero, right down to the nuts and bolts of techniques for insulating around electrical penetrations and skylights, with diagrams and illustrative photos.

There is an explanation of how to calculate the European Energy Unit baselines and achieve the lowest figure possible.

Coastal Maine Botanical Garden
Coastal Maine Botanical Garden    photo courtesy Robert Benson

Fresh air ventilation methods are highlighted, as sealed building envelopes do not by definition allow outside air to leak in, but indoor air quality is as fundamental as natural light to a healthy biophilic building. In terms of mechanical heating, cooling and ventilation systems, technology including ground-source heat pumps and air-source heat pumps are detailed, as are low-tech methods such as ceiling fans.

Maclay provides a methodology for calculating HVAC requirements and corresponding energy use based on the occupancy of spaces, factoring in considerations such as the plug-loads of items such as computers in commercial office spaces and the process loads of cooking equipment in commercial kitchens.

There are also numerous case studies including outstanding biophilic projects around the world, detailed technical notes on projects like the deep energy retrofit of New York’s iconic Empire State Building, new multi-family housing projects, and both new and refurb projects for commercial offices, educational institutions and industrial facilities.

Wind NRG Partners Campus
Wind NRG Partners Campus      photo courtesy Wind NRG

Maclay practises what he preaches, having lived for 25 years in the Dimetrodon, an off-grid community co-housing project he designed and also helped build in rural Vermont. His firm’s office is also Net Zero, and is detailed in the book as an example of retrofitting and repurposing a heritage structure.

Maclay says the practical aspects of his work relate to his belief that it is important to communicate with those who hold the mechanistic worldview in their language. As a matter of course, the principles of Net Zero underpin every design his practice does: a well-sealed and well-insulated building envelope for energy efficiency and comfort, use of natural light and ventilation, non-toxic materials with a sound lifecycle and footprint, and the ability to utilise renewable sources to meet all power needs. This type of design he terms “Net Zero Ready”.

“I design everything as a Net Zero Ready building, then show the client the options for adding renewable energy, so the owner and tenant can look at the costs,” he said.

“One of the things I’ve learned: you need to speak to people where they come from. Often people with very different politics to mine have relatives with asthma, so that is what makes sense for them.”

Wind NRG Partners Campus interior
Wind NRG Partners Campus interior      photo courtesy Carolyn Bates

Maclay’s own home is triple-glazed with high performance glass. He said that for people on high incomes who don’t have energy bills as a concern, the discussion can instead revolve around comfort, as when materials are not well-insulated and are themselves cold, the human body loses radiant heat to the surrounding building.

“So we talk about comfort, about connection to views and light. Pretty much everyone wants to be comfortable,” he says.

“The reality is that the environmental benefits of Net Zero buildings are really quite great.”

Vermont gets extremely cold, with winter temperatures well below freezing. So another benefit Maclay points out to clients is that when the power goes out, as it frequently does for anything between a few hours to a day or two, a well-insulated home is less likely to become excessively cold even without mechanical or electrical heating, and the pipes are less likely to freeze and burst. Few people can’t see the upside of that, he says.

“A home is much more resilient to climate with insulation,” he says. “When you insulate well, you have a much more forgiving building.”

WheelerBrook 18 unit multi-family affordable housing project
WheelerBrook 18 unit multi-family affordable housing project          photo courtesy Maclay Architects

Maclay says he believes we are at a tipping point, where we can more easily build or retrofit Net Zero buildings incorporating renewable energy because the price of the technologies is coming down to the point where they are competitive with fossil fuel sources. He also points out that there are some aspects of Net Zero building such as sealing the building that are cashflow positive from day one. The return on investment and payback periods of a wide variety of sustainability initiatives are also detailed in the book.

Ultimately, Maclay says, metrics are needed.

“We need to be visionaries, and we also need to get down to earth and get things done.

“Some books about this topic are really good on that [visionary aspect], but when you get down to the metrics some of them are pretty bogus.

“One of the things we have pushed for is switching from relative metrics [systems similar to BASIX] where the home is rated as a percentage against an “average” – to absolutes. Zero is an absolute standard we need. It’s similar to fuel efficiency for cars, there is one number, and you can look at it.

“We need to have some very simple metrics.”

The global project picture he outlays in the book is important, he said, in terms of getting people thinking beyond individual buildings to the bigger pictures of Net Zero villages, towns and whole societies.

“There’s a segment in architecture which is about getting the pretty photo in a magazine, and that is about sculpture and art and aesthetics, but design is about human life. My attitude is… we are generating living organisms when we build buildings, they should be about the experience of daily life, and have things like windows that look out on a special garden or view as you go about your day.

“And with the workplace and where people work, why wouldn’t we think of the workplace as an ecosystem? With places to get away, a cafe, small rooms for private space, and bigger team spaces. So going to work becomes literally like going into a forest and the experience of it relates to how people feel throughout their day. That’s the way our workplaces want to be – like a village, like an ecosystem.

“It’s not just about making pretty pictures, it’s hopefully about making a beautiful world that people are living in and enriched by, and one where they are living richer lives.”

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  1. This is also happening outside the ‘built’ environment. There is an increasing trend for products and services to be designed ‘to do more good’. I see it happening under a variety of labels, including Blue Economy, Circular Economy, Biomimicry, Natural Capitalism and Regenerative Business.
    It’s a basic and fundamental mindset shift that started decades ago and which has since been proved by all sorts of companies. Read “Business Lessons from a Radical Industrialist” for some great examples.