Whether we’re talking about new or existing buildings, sustainable zero-energy communities are the wave of the future as we tackle the climate crisis

Chuck

<p>Although the coronavirus pandemic has dominated recent headlines, climate change&nbsp;<a href="https://www.scientificamerican.com/article/why-co2-isnt-falling-more-during-a-global-lockdown/">hasn&rsquo;t gone away</a>. Many experts are calling for a &ldquo;<a href="https://www.carbonbrief.org/leading-economists-green-coronavirus-recovery-also-better-for-economy">green&rdquo; economic recovery</a>&nbsp;that directs investments into&nbsp;<a href="https://time.com/5835402/green-stimulus-climate-change-coronavirus/">low-carbon energy sources and technologies</a>.</p>
<p>Buildings account for&nbsp;<a href="https://www.eia.gov/totalenergy/data/monthly/pdf/flow/total_energy.pdf">40% of total energy consumption in the U.S.</a>, compared to 32% for industry and 28% for transportation.&nbsp;<a href="https://www.cpuc.ca.gov/ZNE/">States</a>&nbsp;and&nbsp;<a href="https://www.boston.gov/sites/default/files/embed/file/2019-10/city_of_boston_2019_climate_action_plan_update_4.pdf">cities</a>&nbsp;with ambitious climate action plans are working to reduce emissions from the building sector to zero. This means maximizing energy efficiency to reduce building energy use, and then supplying the remaining energy needs with electricity generated by carbon-free sources.</p>
<p>My colleagues and I study the best ways to&nbsp;<a href="https://www.nrel.gov/buildings/">rapidly reduce carbon emissions from the building sector</a>. In recent years, construction designs have advanced dramatically. Net zero energy buildings, which produce the energy they need on site from renewable sources, increasingly are the default choice. But to speed the transition to zero carbon emissions, I believe the United States must think bigger and focus on designing or redeveloping entire communities that are zero energy.</p>
<p>Tackling energy use in buildings at the district level provides economies of scale. Architects can deploy large heat pumps and other equipment to serve multiple buildings on a staggered schedule across the day. Districts that bring homes, places of work, restaurants, recreation centers and other services together in walkable communities also significantly reduce the energy needed for transportation. In my view, this growing movement will play an increasingly important role in helping the U.S. and the world address the climate crisis.</p>
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<h2>Ambient loops heat and cool</h2>
<p>Heating and cooling are the biggest energy uses in buildings. District design strategies can address these loads more efficiently.</p>
<p>District heating has&nbsp;<a href="https://www.euroheat.org/news/district-energy-in-the-news/top-district-heating-countries-euroheat-power-2015-survey-analysis/">long been used in Europe</a>, as well as on some U.S. college and other campuses. These systems typically have a central plant that burns natural gas to heat water, which then is circulated to the various buildings.</p>
<p>To achieve zero carbon emissions, the latest strategy uses a design known as an&nbsp;<a href="https://www.integralgroup.com/wp-content/uploads/2017/06/IntegralGroup_District-Energy-101.pdf">ambient temperature loop</a>&nbsp;that simultaneously and efficiently both heats and cools different buildings. This concept was first developed for the Whistler Olympic Village in British Columbia.</p>
<p>In a typical ambient loop system, a pump circulates water through an uninsulated pipe network buried below the frost line. At this depth, the soil temperature is near that of the yearly average air temperature for that location. As water moves through the pipe, it warms or cools toward this temperature.</p>
<p>Heat pumps at individual buildings or other points along the ambient loop add or extract heat from the loop. They can also move heat between deep geothermal wells and the circulating water.</p>
<p>The loop also circulates through a central plant that keeps it in an optimum temperature range for maximum heat pump performance. The plant can use cooling towers or wastewater to remove heat. It can add heat via renewable sources, such as solar thermal collectors, renewable fuel or heat pumps powered by renewable electricity.</p>
<p><span style="color: #172940; font-family: Inter, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', serif; font-size: 24px; font-weight: bold;">Putting wastewater to use</span></p>
<p>One example of a potentially zero-energy district currently being developed, the&nbsp;<a href="https://www.thesolutionsjournal.com/article/national-western-center-sun-valley-ecodistrict-infusing-large-scale-urban-development-projects-sustainability/">National Western Center</a>, is a multi-use campus currently under construction in Denver to house the annual National Western Stock Show and other public events focused on food and agriculture.</p>
<p>A 6-foot-diameter pipe carrying the city&rsquo;s wastewater runs underground through the property before delivering the water to a treatment plant. The water temperature stays within a narrow range of 61 to 77 degrees F throughout the year.</p>
<p>The wastewater pipe and a heat exchanger transfer heat to and from an ambient loop circulating water throughout the district. The system provides heat in winter and absorbs heat in the summer via heat recovery chillers, which are heat pumps that can simultaneously provide heating and cooling. This strategy serves individual buildings at very high efficiency.</p>
<p>Electricity used to operate the heat pumps, lighting and other equipment will come from on-site photovoltaics and wind- and solar-generated electricity imported from off-site.</p>
<h2>Integrated low-energy housing in Austin</h2>
<p>Another district that will minimize carbon emissions is the&nbsp;<a href="https://www.whispervalleyaustin.com/living-ecosmart/net-zero-energy/#geothermal">Whisper Valley Community</a>, under construction in Austin, Texas. This 2,000-acre&nbsp;<a href="https://www.businesswire.com/news/home/20190402005438/en/Taurus-Investment-Holdings-Receives-Investment-Shell-New">multi-use development</a>&nbsp;includes 7,500 all-electric houses, 2 million square feet of commercial space, two schools, and a 600-acre park. Its design has already received a&nbsp;<a href="https://www.greenbuildermedia.com/design/2019-green-home-of-the-year-award-winner-loud-as-a-whisper">green building award</a>.</p>
<p>Whisper Valley will run on an integrated energy system that includes an extensive ambient loop network heated and cooled by heat pumps and geothermal wells located at each house. Each homeowner has the option to include a 5-kilowatt rooftop solar photovoltaic array to operate the heat pump and energy-efficient appliances, including heat pump water heaters and inductive stovetops. According to the developer, Whisper Valley&rsquo;s economy of scale allows for a median sale price US$50,000 below that of typical Austin houses.</p>
<p><span style="color: #172940; font-family: Inter, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', serif; font-size: 24px; font-weight: bold;">The future of zero-energy communities</span></p>
<p>The National Renewable Energy Laboratory, Lawrence Berkeley National Laboratory, and other project partners are developing an open source software development kit called&nbsp;<a href="https://www.nrel.gov/buildings/urbanopt.html">URBANopt</a>&nbsp;that models elements of zero energy districts, such as building efficiency/demand flexibility strategies, rooftop photovoltaic arrays and ambient loop district thermal systems. The software can be integrated into other computer models to aid in the design of zero energy communities. NREL engineers have been engaging with high-performance district projects across the country, such as the National Western Center, to help inform and guide the development of the URBANopt platform.</p>
<p>The projects I&rsquo;ve described are new construction. It&rsquo;s harder to achieve net zero energy in existing buildings or communities economically, but there are ways to do it. It makes sense to apply those efficiency measures that are the&nbsp;<a href="https://resstock.nrel.gov/factsheets">most cost-effective to retrofit</a>, convert building heating and cooling systems to electricity and provide the electricity with solar photovoltaics.</p>
<p>Utilities are increasingly offering&nbsp;<a href="https://news.energysage.com/whats-the-cheapest-time-of-day-to-use-electricity-with-time-of-use-rates/">time-of-use rate schedules</a>, which charge more for power use during high demand periods. Emerging home energy management systems will allow home owners to heat water, charge home batteries and electric vehicles and run other appliances at times when electricity prices are lowest. Whether we&rsquo;re talking about new or existing buildings, I see sustainable zero energy communities powered by renewable energy as the wave of the future as we tackle the climate change crisis.</p>
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<p><em>This article is also published on <a href="https://theconversation.com/buildings-consume-lots-of-energy-heres-how-to-design-whole-communities-that-give-back-as-much-as-they-take-133871" target="_blank" rel="noopener">The Conversation</a>. illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability &amp; Energy writers, their opinions do not necessarily represent those of illuminem.</em></p>
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Buildings consume lots of energy – here’s how to design whole communities that give back as much as they take

The most important thing we must do to halt climate change is rapidly transition from fossil fuels to carbon-free energy alternatives

Jeffrey

<p>If the COVID-19 pandemic has taught us anything it is that an early, science-based response to a rapidly unfolding disaster is critical. In recent years we have witnessed the mounting effects of climate change in the form of&nbsp;<a href="https://www.ncdc.noaa.gov/billions/">droughts, worsening storms, more frequent floods and record wildfires</a>. Many of these burdens fall inequitably on citizens with lower incomes. Although we need to address the many causes of greenhouse gas (GHG) emissions,&nbsp;<a href="https://www.eia.gov/energyexplained/energy-and-the-environment/where-greenhouse-gases-come-from.php">three-quarters of U.S. emissions come from burning fossil fuels</a>. Thus, the most important thing we must do to halt climate change is rapidly transition from fossil fuels to carbon-free energy alternatives.</p>
<p>Fortunately, the solutions at hand have improved markedly in the last 10 years. The costs of electricity from&nbsp;<a href="https://www.lazard.com/perspective/levelized-cost-of-energy-and-levelized-cost-of-storage-2020/">solar and wind energy</a>&nbsp;have declined dramatically and are now the cheapest sources of electricity in much of the U.S. &mdash; about one-quarter the cost of new nuclear power. There is growing agreement on a&nbsp;<a href="https://www.colorado.edu/rasei/sites/default/files/attached-files/accelerating_the_us_clean_energy_transformation_final.2.pdf">course of action</a>&nbsp;for addressing climate change:</p>
<p>1. Maximize energy efficiency.</p>
<p>2. Deploy low-cost solar and wind electricity as rapidly as possible. A&nbsp;<a href="https://www.climaterealityproject.org/blog/what-are-clean-electricity-standards">clean electricity standard (CES)</a>&nbsp;that requires 100 percent of electricity to be carbon-free by 2035 is the best tool to get there, and Congress needs to act.</p>
<p>3. Electrify as many of our energy uses as possible to take advantage of this carbon-free energy.</p>
<p>4. Continue to develop&nbsp;<a href="https://medium.com/cleantech-rising/whats-the-difference-between-carbon-neutral-zero-carbon-and-negative-emissions-baa83c76fc8d">carbon-free and carbon-neutral fuels</a>&nbsp;for those limited applications that are difficult or very expensive to electrify.</p>
<p>How can we have a reliable grid with largely weather-dependent generation? There are a variety of ways we can address this. For almost a decade, NREL and others have developed best practices to&nbsp;<a href="https://www.nrel.gov/docs/fy13osti/60451.pdf">integrate variable renewables</a>&nbsp;into the grid at least cost. Options include&nbsp;<a href="https://www.nrel.gov/docs/fy15osti/63037.pdf">expanding balancing areas to minimize variability</a>, using advanced weather forecasting and&nbsp;<a href="https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2019/Feb/IRENA_Increasing_time_granularity_2019.pdf?la=en&amp;hash=BAEDCA5116F9380AEB90C219356DA34A5CB0726A">shortening grid dispatch times</a>, &nbsp;<a href="https://www.utilitydive.com/news/propelling-the-transition-new-and-better-transmission-is-key-to-zero-carbo/582331/">adding transmission</a>&nbsp;and storage, utilizing&nbsp;<a href="https://www.energy.gov/sites/prod/files/2020/04/f74/bto-see-action-GEBs-valuation-20200410.pdf">demand flexibility in buildings</a>&nbsp;and many others.</p>
<p><a href="https://www.2035report.com/">Many analysts</a>&nbsp;see a clear path to achieving an 80 or 90 percent renewable electricity grid. Addressing that last 10 or 20 percent will also likely require long-term storage as well as grid modernization including improved&nbsp;<a href="https://www.irena.org/publications/2017/May/Adapting-Market-Design-to-High-Shares-of-Variable-Renewable-Energy">market design</a>. Although some observers have called for a&nbsp;<a href="https://www.newsweek.com/right-path-forward-climate-change-opinion-1571169">massive R&amp;D effort</a>&nbsp;to develop innovative solutions to the climate crisis, the truth is that we already have the technologies we need to solve most of the problem, and our chief focus must be on enabling and deploying them.</p>
<p>That&rsquo;s not to imply this will be easy. 2020 was a&nbsp;<a href="https://www.cbsnews.com/news/solar-wind-energy-united-states-2020/">record year</a>&nbsp;for new U.S. wind and solar electric capacity additions, at about 33,000 megawatts. To achieve a carbon-free grid by 2035, we will have to install an average of roughly&nbsp;<a href="https://www.2035report.com/">two to three times</a>&nbsp;that amount every year over the next 15 years. The actual amount needed will depend on factors such as how quickly we electrify transportation, buildings, and industry.</p>
<p>How can we make that goal more achievable? First, the more efficient we make our transportation, buildings, and industrial sectors, the less additional electricity we will need. Another important step is to&nbsp;<a href="https://cen.acs.org/energy/nuclear-power/nuclear-power-help-save-us/97/i37">keep our existing nuclear reactor fleet running</a>&nbsp;for as long as we can safely do so. We can also electrify in stages starting with those energy uses that provide the biggest immediate climate change benefits.&nbsp;<a href="https://www.epa.gov/greenvehicles/fast-facts-transportation-greenhouse-gas-emissions">Cars and trucks</a>&nbsp;account for over 80 percent of our transportation-related GHG emissions, and battery electric vehicles use energy much more efficiently than internal combustion engines, so electrifying that segment is a priority.</p>
<p>Following vehicle electrification, using&nbsp;<a href="https://rmi.org/its-time-to-incentivize-residential-heat-pumps/">heat pumps</a>&nbsp;to electrify heating in buildings and low-temperature industrial processes is next. Electrifying new buildings avoids the capital investment and long-term commitment in natural gas equipment and piping. (It will take somewhat more effort to economically electrify existing buildings.) Electrifying higher-temperature industrial processes can wait until the grid is sufficiently carbon-free.</p>
<p>What about uses that are hard to electrify like long-distance aviation and ocean-going cargo ships? Biofuels can play a role here, although they face&nbsp;<a href="https://www.epa.gov/environmental-economics/economics-biofuels">challenges</a>&nbsp;in land use, biodiversity tradeoffs, biomass transportation costs and net carbon impacts. There is increasing interest &mdash; and debate &mdash; regarding the&nbsp;<a href="https://about.bnef.com/blog/liebreich-separating-hype-from-hydrogen-part-two-the-demand-side/">role of hydrogen</a>&nbsp;(and&nbsp;<a href="https://cen.acs.org/business/petrochemicals/ammonia-fuel-future/99/i8">ammonia produced from hydrogen</a>). Renewable electricity can produce &ldquo;green&rdquo; hydrogen from water via electrolysis. But there are inefficiencies and expenses associated with producing, storing, transporting and utilizing the hydrogen. Hydrogen can also be combined with carbon (captured from biomass, industrial processes or &mdash; most expensively &mdash; from the air) to produce&nbsp;&nbsp;<a href="https://www.sciencedaily.com/releases/2021/05/210506142118.htm">synthetic &ldquo;drop-in&rdquo; hydrocarbon fuels</a>, which are easier to use but even more expensive to produce. Fortunately, the applications that might need these fuels are responsible for only a small percentage of greenhouse gases.&nbsp;</p>
<p>The Biden administration is setting an example for the rest of the world by targeting 2050 for a&nbsp;<a href="https://www.energy.gov/articles/how-were-moving-net-zero-2050">net-zero carbon economy</a>. In this context &ldquo;net-zero&rdquo; generally means we are removing as much carbon dioxide from the atmosphere as we are adding.&nbsp; After the important step of stopping deforestation, there are a variety of ways we can remove carbon dioxide, all of which have their tradeoffs. But the most cost-effective thing we must do is to not emit CO2 in the first place. Thus, any efforts to remove CO2 from the air must not detract from efforts to rapidly replace fossil fuels with zero-carbon energy.</p>
<p>We already have the technologies we need to solve most of the problem, and we have a variety of options for getting the rest of the way there. The biggest challenges are not technological but rather political and sociological. Strong policies are needed, and to realize them, we must rise above our divisive politics. Fossil fuels are cheap, partly because of continuing&nbsp;<a href="https://www.nrdc.org/experts/danielle-droitsch/time-us-end-fossil-fuel-subsidies">subsidies</a>, and these must be removed. Putting a&nbsp;<a href="https://energyinnovationact.org/">price on carbon</a>&nbsp;that reflects its social cost will help. But a new focus that follows science, together with the prospects for a strong post-pandemic economic expansion and the many opportunities it offers, make this the ideal time to finally address the climate change crisis. The COVID-19 pandemic was devastating for people and economies around the world &mdash; a future with unabated climate change would be far worse.</p>
<p><em>This article is also published on <a href="https://thehill.com/opinion/energy-environment/553871-what-a-rapid-transition-from-fossil-fuels-to-carbon-free-energy/" target="_blank" rel="noopener">The Hill</a>. <span style="font-family: Inter, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', serif;">illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability &amp; Energy writers, their opinions do not necessarily represent those of illuminem.</span></em></p>

Chuck Kutscher

Chuck Kutscher

Buildings consume lots of energy – here’s how to design whole communities that give back as much as they take

What a rapid transition from fossil fuels to carbon-free energy alternatives looks like

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