Should I Build or Buy an Existing Home – Which is Better for the Environment?

birdhouse in the shape of a house - is it greener to build or buy a house

The real estate market is very difficult to get into, so if you find yourself in a position to be able to buy a home, you’ll want to make the absolute most of your purchase. You’ll likely be thinking about location, amenities and possible resale value when you start your home-buying search. You might also be thinking green as part of your investment strategy, and if you are, you are clever to do so. 68% of home buyers want homes with green qualities, according to Realtor Magazine.

One of the central questions for many prospective homeowners is whether to build or to buy an existing home. But what’s the greenest choice? This article will take you through some considerations.


New homes are least green when it comes to waste. According to Nigel Maynard of Builder Magazine, the average 2000 ft2 house “generates about four to seven tons of waste” during construction, with little of it being recycled. It’s a problem the industry is increasingly coming to terms with, but you’re still much more likely to encounter new home builders who send their waste to landfill than those who recycle or reuse it.

Architect Carl Elefante argues that “the greenest building is one that is already built.” With existing homes, waste is less of an issue, and the emissions associated with new construction have already happened, so you won’t be generating more. Renovations also contribute, of course, to the waste that the construction industry sends to landfills every year, but the volume of new materials you use isn’t likely to compare to a new build.


The materials you find in an existing home could range widely from sustainable to alarming. This is especially true of pre WWII era homes, which come from a time that was much better than we are at reusing and recycling things but a bit laissez-faire about toxicity.

The plus side of living in an existing home made with non-eco-friendly materials is that any off-gassing processes will probably be complete, unlike new homes made with similar materials, which will be off-gassing while you live there.

Whether you build or buy a home that’s already built, you can, of course, replace any existing materials with more sustainable ones. The advantage in a new home, if you find a developer who offers sustainable options, would be the ability to choose sustainable materials in the first place and avoid toxic materials altogether.

Energy Efficiency

cottage in the mountains - is it greener to build or buy a house

Better insulation, more efficient HVAC systems, low-E windows and tighter building envelopes are just some of the green advantages new homes have over older homes. New homes can offer many built-in, high-tech options, as well, like heat recovery or solar systems.

That said, while contemporary building codes require new homes to be built to stricter efficiency standards, any home can be retrofitted and brought up to that standard. High performing insulation, high-efficiency HVAC systems and ENERGY STAR appliances fit just as well in old homes as they do in new ones.

A Note About Housing Size

The average home size in the U.S. has increased 62% since 1973. While HVAC systems have become much more efficient since the 1970s, Drew DeSilver of the PEW Research Center explains that the “growing girth” of modern homes “wipes out nearly all the efficiency gains” of modern HVAC systems because there’s so much more space to heat and cool.

Senior lecturer in architecture Iman Khajehzadeh finds similar trends in house sizing in New Zealand. His research concludes that despite the growing size of homes, families still spend most of their time in what he calls “the ‘core’ house:” the bedrooms, kitchen, dining room and living room.

“On average,” he says, “New Zealanders who live in owner-occupied houses use double the energy compared to what is required for living in that ‘core’ house.” If you purchase a new home, you’ll probably end up buying more space than you actually live in and using more energy than you need to for the duration of your time there.

Housing Site

Building in a new housing development will mean few to no options to minimize the effects of site disruption. If this is important to you, you’ll have to find a builder who shares your priorities and has a plan to mitigate site disturbance.

If you have the luxury of freely choosing your building site, you might also have the luxury of determining what happens to the site and all the flora and fauna that already live there. You might be able to give directions about cutting as few trees as possible, saving native plants, replanting trees that are destroyed when the home is built or working with conservation organizations to minimize the impact of your new home.

With existing homes, site disruption has already happened and there’s frankly not much you can do about it. You can, however, choose your location with an eye to environmental friendliness. A 2011 EPA study explains that households in high density areas “produce about half the emissions of households in areas with very low density.” This has to do with house size and house type (attached homes and homes in multi-family units are smaller and share walls, requiring less energy), as well as transportation factors.

The study authors argue that while the housing industry has focused on the development of energy efficient homes (which they in no way state is a bad idea), we should also be looking to “compact, location efficient, transit-oriented” forms of housing to reduce our carbon footprints. You’re much more likely to find that in existing homes than new builds.

Conclusion – To Build or Buy an Existing Home?

Whether you build or buy an existing home, the green-ness of it all might, in the end, come down to the choices you’re able to make. Greg Kats makes the case that greener homes are only approximately 2% more expensive to build than conventional homes (despite public perception that green buildings are 17% more expensive). If you can swing that 2%, you might end up with a newly built home that meets your criteria for eco-friendliness.

Regardless of whether your home is new or existing, if you can incorporate renewable energy measures, water-saving features, sustainable finishes and native landscaping, your home is going to be much greener than average. The important thing to consider is what green features you can put into a home yourself and what features you’ll need a home to come with already.

Feature image: David Gonzales; Image 1: Quang Nguyen Vinh

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