Sustainable, green energy technology, like solar power and electric vehicles, have captured much of the world's attention in the fight against global warming. Another less obvious solution has also garnered attention. Because buildings have been established as a major source of greenhouse gas emissions, employing efficiency measures to reduce the consumption of gas and electricity in them and the emissions these cause are now also championed as an effective way to fight climate change.
How effective is this technology and how much emphasis should the world place on reducing building emissions?
Buildings and the Pollution They Emit
It is a difficult proposition to embrace: The very buildings we construct and inhabit, both at work and at rest, are contributing to the existential crisis of global warming. The numbers are impossible to ignore. According to the International Energy Agency (IEA), residential and commercial buildings emitted about nine gigatons of carbon in 2020.
Other sources paint a similar picture. According to Architecture 2030, an organization dedicated to addressing climate change in the building industry, buildings generate almost 40% of global carbon emissions. 28% comes from the operations of existing buildings. The remaining 11% is generated by the materials used and the construction of new buildings.
What causes emissions from buildings? They consume massive amounts of energy. Most of it is to support their functionality and the comfort of their inhabitants—people. Over one third is used for heating, ventilation, and cooling. Other sources of consumption include lighting, water heating, refrigeration, appliances, computers, and other electronics.
Most of these functions rely on electricity, but they are also powered by natural gas and other fossil fuels, all of which emit greenhouse gasses. According to the US Department of Energy (DOE), the US buildings sector accounts for about 76% of the nation's electricity use and 40% of all its primary energy use and the associated greenhouse gas (GHG) emissions.
Making Buildings More Efficient
The good news is that energy use in buildings can be reduced. These reductions also cut carbon emissions. According to the DOE, building energy use could be reduced by more than 20% by the year 2030 using known technologies, and "much higher savings are technically possible." The American Council for an Energy Efficient Economy (ACEEE) embraces the possibility of “much higher savings.” It asserts that “new homes and commercial buildings could cut their emissions by 70% with efficient design and use of cleaner electricity.” So how do we go about making buildings more energy efficient?
Since heating, cooling, and ventilation consume most of the energy in buildings, they also represent the greatest potential for savings. Reductions can be achieved in two ways: (1) by improving the functionality of devices and appliances, and (2) by improving the way they are controlled. In both cases, modern technology offers many options.
Heat pumps, boilers, furnaces, air conditioning units, and other appliances that control the environment in buildings have become much more efficient in recent decades. More efficient units can be installed in new buildings when they are constructed. Existing buildings have to replace existing appliances with new, more efficient models. Chances are that appliances in buildings that are more than ten years old can, and should be, replaced with a more efficient model.
“New homes and commercial buildings could cut their emissions by 70% with efficient design and use of cleaner electricity.”
The Energy Star rating developed by the US Environmental Protection Agency (EPA) in 1992 is given to appliances that meet certain efficiency standards. It helps consumers make more informed choices about efficiency when they purchase appliances for their home or commercial buildings. According to the EPA, Americans purchased 300 million Energy Star products in 2019. More importantly, in that same year, these products helped consumers save 230 billion kilowatt-hours (kWh) of electricity, avoid $23 billion in energy costs, and achieve 170 million metric tons (187 million tons) of GHG reductions.
Building owners can also achieve great savings in consumption by changing the way they control and manage appliances. Programmable thermostats, for example, allow occupants to adjust the schedule of heating and cooling appliances to turn on at certain times or days of the week. Smart thermostats go even further, using artificial intelligence that "learns" the occupants' behavior. They detect patterns tied to occupancy, outside temperatures, and daily and weekly schedules to create schedules for appliances based on when they are most likely to be needed. These intelligent controls eliminate the use of energy for heating and cooling when the buildings are not occupied or when temperature control is otherwise unnecessary.
Smart controls in buildings can also be applied to lighting. LED fixtures are much more efficient in their energy consumption than other types of lighting. They are also easily paired with digital controls and platforms that allow building owners and managers to control and manage lighting. Occupancy sensors turn on lights only when rooms are occupied. Ambient light sensors adjust lighting according to the amount of daylight that is penetrating a building. Smart lighting, like smart thermostats, also learn from the behavior of building occupants to set schedules and minimize the lighting that is needed. According to the ACEEE, advanced lighting systems can cut energy use in buildings by as much as 45%.
What Are the Major Obstacles to Building Efficiency?
While the technology exists to make buildings more energy-efficient, cost remains a major challenge. Many of the technologies that have been developed are still very expensive. Building owners must make a calculation about energy efficiency: Will the value of the energy saved exceed the cost of the improvements? Recognizing that energy savings do not happen all at once, building owners also must ask how long it will take to recoup the cost of the improvements based on the energy saved over time.
The calculations are different for new and existing buildings. For example, a homeowner who is considering purchasing solar panels coupled with a battery system will make several calculations. Solar roof panels on a typical residential home can cost $20,000 or more. A battery to store power generated by those panels can cost $10,000 or more.
"Building owners must ask how long it will take to recoup the cost of the improvements based on the energy saved over time."
The homeowner in this scenario will have to decide if the $30,000 investment is worth the value of the electricity to be saved. This will depend on a number of factors, including but not limited to the size of the home, the location of the home (how much solar power can be generated), energy use patterns in the home, the cost of the electricity from the local utility, how the purchases will be financed, and how long the owner will live in the home.
Commercial building owners face similar questions on a larger scale. New buildings, commercial and residential, can include the cost of the technology in the upfront cost of the building, which can be wrapped into the financing (mortgage loan). This may be less of a financial shock for the owner or occupant, but it still puts upward pressure on the price of the building.
As technology improves, and the costs come down, balancing these equations may become easier. Meanwhile, utilities continue to wrestle with the questions of rates and incentives for things like electricity that is sold back into the grid from building owners with solar panels. The question of cost-effectiveness remains a challenge for any building owner considering energy efficiency technology.
What About New Buildings?
As noted, adopting energy efficiency in new buildings can be less painful for building owners. While existing buildings remain the larger source of GHG emissions, making new buildings more efficient may represent a more practical way to reduce overall emissions from buildings. Many of the same methods used in existing buildings can make new buildings more efficient. Smart technology like thermostats and other temperature and lighting controls can greatly reduce energy consumption. More efficient heating and cooling systems can also drastically reduce energy demands. Other technologies and approaches to building design, which are less practically applied to existing buildings, can make new buildings also more energy efficient.
For example, energy use in a building can be significantly reduced by changes to what is referred to as the building envelope. This entails applying more efficient materials and technology to the structure and exterior of the building to minimize the loss of energy, the transfer of hot and cold air, the penetration of sunlight, and other factors that affect the indoor environment. Roofing materials, insulation in the walls and roof space, and advanced window insulation technology can help create a more secure and efficient environment within buildings that minimizes the loss of energy and the need to adjust conditions through lighting or air temperature controls. According to the Advanced Energy Economy (AEE), building envelope technologies can reduce the energy demands in buildings for heating and cooling alone by as much as 40%.
Similarly, buildings can be constructed more strategically to minimize the impact of the surrounding environment. So-called passive design entails situating and positioning buildings to minimize or maximize, depending on the environment, the penetration of sunlight to affect inside temperatures and reduce the need for heating or cooling. The same methods can be applied to capture natural light in a similar way.
Lastly, some building complexes like hospitals or universities can be designed with cogeneration systems. These capture heat created by onsite power generation facilities and reuse it for air and water heating inside the buildings.
What More Can Be Done?
The contribution of buildings to global warming has been well established. The need to reduce those emissions is also clear. Furthermore, a myriad of technologies and know-how has been developed to help buildings reduce their carbon footprint. The cost of this technology can still be prohibitive for many commercial and residential building owners. Incentives, policies, and supportive energy rate structures adopted by government and utilities, will serve to encourage more investment in energy efficiency and the much-needed reduction of energy use and carbon emissions from new and existing buildings.
*Rick Laezman is a freelance writer in Los Angeles, California, US. He has a passion for energy efficiency and innovation. He has been covering renewable power and other related subjects for more than ten years.