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Zero Energy Communities

“It’s estimated that around 40% of all energy consumption in the United States is accounted for by our buildings, which dwarfs both industry and transportation.”

By: Adi Gaskell, Contributor

At the start of the year, the World Economic Forum’s annual risks report cited climate change as the foremost challenge facing the world today.  Against the backdrop of a year in which the climate emergency was at the top of so many agendas, this prominence was understandable.  Despite being shunted to the side somewhat by the coronavirus pandemic, the desire for the post-covid world to be a greener one than the pre-covid world remains.  Indeed, a new paper from the European Commission Joint Research Centre (JRC), makes the case for a re-establishment of the human, social, and economic capital that has been eroded by the pandemic, and urges us to make society both greener and fairer.

“It seems that the planet was waiting for the Coronavirus to rest,” says Katerva expert Mahmoud ElBurai, VP of the International Real Estate Federation.

If the post-covid economic recovery is to be a green one, then our buildings are going to be fundamental.  It’s estimated that around 40% of all energy consumption in the United States is accounted for by our buildings, which dwarfs both industry and transportation.  It’s perhaps no surprise, therefore, that cities such as Boston are striving to make emissions from the building sector as low as possible, and potentially even zero.  This will require not only maximizing the energy efficiency of buildings, but also ensuring what energy they do use is from carbon-free sources.

Thankfully, net zero energy buildings, which produce all of the energy they need on site, are increasingly becoming the default choice, but to date, these developments have been limited to single buildings rather than developing entire zero energy communities.  Such a community-led approach not only provides opportunities for economies of scale, but provides the opportunity to make more liveable communities that place homes, workplaces, recreational centers, and other key amenities within walking distance of all.

Keeping cool

The biggest use of energy in most buildings is in heating them up, or cooling them down.  There are ways of designing communities to make both more efficient.  For instance, in many European countries, district heating systems, which have a central plant that heats water before then circulating the water to the various buildings, have a long history of usage.

Another burgeoning strategy is the use of ambient temperature loops, which both heat and cool buildings simultaneously.  It was a concept developed in Canada for the 2010 Winter Olympics, and involves a pump circulating water through a pipe network buried beneath the frost line, where the soil temperature is more akin to the average air temperature in that location.  As the water moves through the pipe, it either warms or cools toward this temperature.  Different heat pumps throughout the community form a loop and add or remove heat from the loop.

The loops typically send water through a central plant that aims to keep it at an ideal temperature for maximum performance, and cooling towers are often used to help with the removal of excess heat.  Heat can also be added to the loop via renewable energy sources, such as solar thermal collectors.

Efficient use of water

A great example of such systems in action is the National Western Center, in Denver, which is designed to provide a home for various food and agriculture-related public events.  The facility is supported by a 6-foot diameter pipe that carries wastewater from the city to a treatment plant, with the system designed to keep the temperature between 61 and 77 degrees fahrenheit all year round.

The pipe system transfers heat to and from the ambient loop that circulates water throughout the region, providing heat during the winter and cooling during the summer, thus providing extremely energy efficient services to buildings across the city.  What’s more, the electricity that powers the various lights, heat pumps, and other equipment, comes from solar and wind generators located off-site.

Similarly, the award winning Whisper Valley Community in Austin, Texas, highlights how residential communities can be constructed in an efficient manner.  The multi-use development is designed to house 7,500 all-electric houses alongside two schools, a 600-acre park and some 2 million square feet of commercial space.

The site has an integrated energy system, including an ambient loop network to heat and cool water from geothermal wells built underneath each house.  Each property also has the option to have a 5kw solar array fitted to their roof to operate both the property’s heat pump and appliances.  The developers claim that the economies of scale afforded by the development allow them to offer the homes for around $50,000 less than is common in Austin.

Projects like these are being supported by a burgeoning community of developers.  For instance, the open source URBANopt software development kit models various elements of zero energy districts to encourage their development.  The software is designed to be integrated into various computer models to help with the design and development of zero energy communities.  

The two examples illustrated above are both new developments, and while it’s harder to achieve the same results with existing developments, by including sustainability and energy efficiency at the start, supporters of zero energy communities hope that the technologies that underpin them will become affordable enough to make retrofitting existing communities viable.

Sustainable housing is likely to be vital if society is to successfully tackle the climate emergency, and these projects show the progress being made, and the viability of zero energy communities.  Hopefully they will become the way all new communities are developed in future.

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