Building Energy Efficiency

By Anthony Cheng and Tim Glinski

Introduction

Energy usage in city buildings currently accounts for about one-fifth of the energy consumed worldwide, or about 110 quadrillion British thermal units.¹ This figure is projected to grow by an average of 1.5% per year from 2012 to 2040. This is mainly as a result of growing residential sector demand in lesser-developed countries, with India and China leading the way.¹ The goal of this article is to identify major sources of energy usage in buildings within different developmental contexts and provide solutions for more efficient energy usage.

Context

According to the United Nations Environmental Program’s platform for the COP 15 conference,² the Building Sector has the “largest potential for delivering long-term, significant and cost-effective greenhouse gas emissions, relatively independent of the cost per ton of CO2 equivalent achieved.” With currently available technologies, energy consumption in both new and existing buildings can be cut by 30 to 80 percent in both developed and developing countries.²

Energy use in buildings is used for space and water heating, cooling, lighting, and appliances and equipment. However, the distribution of energy used by each of these sectors depends on multiple factors such as the energy source, price, income level, location, building and household characteristics, weather, equipment types and efficiency, access to delivered energy, availability of energy sources, and energy-related policies. Thus, the types and amounts of energy households use may vary widely within and across regions and countries.

For most countries that are part of the Organisation for Economic Co-operation and Development (OECD), an association of largely more developed nations, energy usage in buildings has not increased, but the makeup of energy use has changed significantly. Analyzing energy usage in the United States in 1978 and in 2005, the energy usage for appliances and electronics such as refrigerators, dishwashers, dryers, and air conditioning has nearly doubled, while space heating has become much more efficient (a 33% reduction in energy cost).³ While each sector has generally become more efficient, increased penetration of water heaters, air conditioners, multiple refrigerators, multiple microwaves, and the like have caused significant changes in energy usage over time. We can use these historical trends to understand possible changes in energy usage distribution in developing countries.

Figure 1.

In non-OECD (namely, developing) countries, residential energy consumption in the non-OECD countries accounted for less than 50% of the world’s total residential energy use in 2012. However, the US Energy Information Agency estimates that they will account for more than 60% of all energy use in 2040, as a result of generally faster economic and population growth than in the OECD countries.¹

In the 2015 United Nations Climate Change Conference, also known as the 21st Conference of Parties (COP21), a new Global Alliance for Buildings and Construction was launched, to spur widespread adoption of today’s best policies and most efficient building materials, designs and technologies. The Alliance hopes to avoid at least 50 percent of projected growth in energy consumption.

Solutions

To achieve the goals laid out at COP21, this article will provide several additional, specific solutions for increasing energy efficiency that are easily implementable and economically favorable.

By retrofitting older buildings to be more energy efficient, energy consumption could be drastically reduced. This can be done through installing better insulation, more efficient thermal regulation, and LED lighting.⁴ For example, by retrofitting the least efficient 16% of buildings in Cambridge, Massachusetts buildings with better insulation, lighting, heating, and cooling systems, the entire city’s natural gas usage (commonly used for heating) would be reduced by approximately 40%.⁵

Most old buildings have poor insulation or lack it entirely; recent studies show that 44% of all energy used in U.S. buildings is used for heating and cooling,⁵ largely due to the inefficiencies in the design of those buildings. The “U value” of a material is a measure of how well it can act as an insulator; the lower a material’s U value, the slower heat transmits through it. This means that a low U-value corresponds to keeping a building cool in hot temperatures and warm in cool temperatures. The U value essentially measures heat loss. Buildings should use triple-pane windows, which have very low U values, in order to ensure that less thermal energy enters or leaves the building.⁶ Furthermore, old windows should be replaced with triple paned windows, to further insulate from outside weather. This replacement can reduce a home’s energy usage by 12% and will by 2050 be a less costly option than a simple double-pane window if installed before 2027.⁷

Insulation effectiveness is measured in a material’s R-values, a measurement of thermal resistance.⁸ Higher R-values correspond to higher resistance to thermal changes, meaning it will keep the building cooler in hot temperatures and warmer in cold temperatures. More dense, thicker insulation will have higher R-values. Furthermore, different insulation materials will have different R-values. As a general rule, the colder the climate, the higher the recommended R-value. In very cold climates, radiant barriers, which are highly reflective materials that emit heat back into the building rather than simply absorb it, should be installed to even more effectively keep heat in. Installing insulation in buildings based on the recommended R-values for the region, especially in old buildings which often have poorly implemented insulation or none at all, will reduce heating and cooling energy usage significantly.

Residential buildings can replace both air conditioning and heating systems with heat pumps, which move energy rather than create it. They take heat energy from outside sources and concentrate it in a manner similar to refrigerators. Heat pumps use on average 50% less energy than other heating and cooling fixtures.⁹ One Angel Square, a building often claimed to be “the world’s greenest building”, uses a geothermal heat pump system that runs air through large pipes underground and then back into the building.¹⁰ Underground, the temperature is kept at an average, year round stable temperature of approximately 18 degrees Celsius. his system can be used for effective energy efficient heating in the winter, and cooling during the summer due to this feature. Unfortunately, these heat pumps, while nearly always more efficient than alternative heating and cooling systems, are less effective in extreme temperatures, due to having to move too much thermal energy to compensate. However, they can be used in conjunction with heat recycling systems that use waste heat from industrial processes to heat nearby residential buildings.⁴ Despite all the positives, there is a high implementation price, discouraging homeowners from replacing temperature regulation systems with heat pumps. The average residential cost of installation for heat pumps ranges from $3957 to $6737.¹¹ But the savings quickly outweigh the costs. For example: when compared to oil systems, heat pumps in the Northeast and Mid-Atlantic regions save on average $948 per year. When compared to electric resistance heating in the same region, the savings add up to approximately $459 per year.¹² The long term cost reduction stemming from heat pump usage makes it the smart choice, but with such high initial costs, convincing the public will be difficult.

Many buildings, especially residential buildings, use inefficient lighting methods. By replacing old light fixtures with LED lights, the overall energy use of these buildings would significantly decrease.⁴ In fact, more energy efficient light bulbs, such as compact fluorescent light bulbs and LEDs use 25% to 80% less energy than incandescent lighting.¹³ While the benefits for increasing energy efficiency in lighting is far higher than the initial costs, the high cost creates a significant barrier to implementation. The cost of replacing an incandescent light bulb with a LED can be as low as $2.50.¹⁴ However, an average of 45 light bulbs in each home, that price climbs to an average of $112.50 for each household.¹⁵ And yet the total savings for that many households would be immense: over a 23 year period, it would cost approximately $201 to operate a single incandescent light bulb, and approximately $38 to operate an LED.¹⁴ For one household, the operating costs then climb to $9045 for incandescent light bulbs, compared to only $1710 for LEDs. Unfortunately, many people are simply unaware of the benefits, or that LED lightbulbs even exist. A survey in 2012 found that over 30% of people in the U.S. were unaware of LED lighting options.¹⁶ Thus, education of and awareness in the populations that own and live in these buildings must occur to allow for the installation of energy-efficient lighting, and any energy efficiency solution in general. Of course, many of these solutions can be mandated by updating and enforcing more environmentally conscious building codes.

Implementation

There are numerous examples of cities trying to implement radical change in building design and city code in an effort to reduce energy usage and increase energy efficiency. One example is Mexico City. On COP21 Buildings Day (December 3rd, 2015), Mayor Mancera of Mexico City, announced at Buildings Day that “it is moving forward to integrate building energy performance in local construction codes, retrofitting hospitals with solar hot water and efficiency measures, and auditing and retrofitting municipal buildings”.¹⁷ In June of 2016, Mexico City announced the final publication of updated construction regulations and building codes for the city.¹⁸ In conjunction with the Building Efficiency Accelerator (BEA), one of the Global Alliance’s six Accelerator programs, Mexico City has pledged to address issues such as “thermal insulation, solar-powered water heaters, efficient lighting, mechanical systems, thermal and optical features in glass, [and] energy efficiency in pumping systems and elevators” in this new city-wide standard. According to the Building Efficiency Initiative, these changes will help new and retrofitted buildings meeting these guidelines to reduce their energy usage by up to 20 percent.

While the talks at the 21st Conference of the Parties outlined the goals established for building energy efficiency, the 22nd Conference, COP22 in Marrakesh has been dubbed the ‘Action’ COP, planning out the steps to meet the terms of the Paris treaties. Many actors, including specially designated “Green Building Councils” (GBCs), have continued provide specific solutions such as sustainable housing and technical guidelines for retrofitting buildings.¹² COP22 recommends investing an additional US$220 billion annually by 2020, an about 50% increase on 2014 investments in energy-efficient buildings by reallocating about 3% of the current total global annual investment in construction activity (roughly US$8.5 trillion in 2014) in order to reach the goals laid out in COP21.¹⁹ The implementation of specific solutions outlined in this article can help achieve those goals and lead to more sustainable buildings worldwide.