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What is energy efficiency and how does it help reverse climate change?

Energy efficiency is in the spotlight more these days when the topic of climate change arises. It’s not obvious how the two are linked. Let’s look at exactly what it means to increase a building’s energy efficiency and how it helps reverse climate change.

What Is Energy Efficiency?

Building energy efficiency is avoided energy use. Energy efficiency is improved by changing building operations through mechanical or behavioral means that decrease energy use, aka save energy. Example energy efficiency projects are replacing fluorescent lighting for LEDs, replacing single pane with double pane windows or as simple as turning off the lights when you leave the room.

How is it calculated?

Energy saving analysis begins by first gathering current energy use data from utility data or monitoring equipment. The industry defines the current amount of energy used as the baseline. Energy engineers then calculate expected energy use which would result from the project. If it is a good project, the expected energy use will be significantly less than the baseline use. Engineers use tried and true analysis to calculate these expected values which varies by project type. They also use project costs in their analysis to provide financial metrics for decision making.

When looking at a building for energy efficiency opportunities, energy auditors will deliver a list of measures, aka potential energy saving projects. This table is an example of a measure list.

energy audit report table eems efficiency measures savings projects payback kw engineering consultant li large

What is the difference between electricity consumption and peak demand?

You can see savings estimates for electricity (kWh), peak demand (kW) and gas savings (therms) in the table above. Energy consumption is measured in kilowatt hours (kWh) over time. Avoided energy use is labeled as ‘electricity savings’ above.

Peak demand, billed for non-residential customers, is the largest instance of power use at a given time, typically a rolling 15-minute window. It is measured in kilowatts (kW) and different than consumption in that it is a rate. It measures the rate at which you use energy per unit of time. So, the more energy you use in that 15-minute window, the bigger your peak demand will be.

How do buildings save energy?

There are so many ways to save energy in buildings. The simplest way to think of reducing consumption (not demand) is by changing either the amount or duration you consume energy.


As shown in the graphic above, the easiest, and typically cheapest, way to save energy is by reducing the time which equipment runs through modifications to existing controls and scheduling. The other part of the equation are more expensive, complicated projects which reduce energy consumption with more efficient equipment.

How do you verify energy savings?

Engineers verify savings by obtaining post-install energy use data either through utility bills or monitoring equipment and comparing that data to the baseline. So in the end there’s nothing concrete about energy savings except for your brand new windows, thermostat, lights, etc. But when energy efficiency projects are done well the best proof is your lower utility bill each month.

What Does Energy Efficiency Have to Do with Climate Change?

There’s a direct link between energy use and climate change. Greenhouse gases (GHGs) are gases that trap heat in the atmosphere causing increases in temperature. Carbon dioxide (CO2) is a common GHG and some others include methane, nitrous oxide and fluorinated gases. In the U.S. most GHG emissions come from burning fossil fuels such as coal, petroleum, natural gas and hydrocarbon gas liquids.

Since fossil fuels contain mostly carbon and hydrogen, when burned oxygen combines with carbon, forming CO2 which enters the atmosphere and the reaction also releases energy. We use the energy for producing electricity in power plants. CO2 also builds up in the atmosphere, increasing by more than a third since the Industrial Revolution contributing to increases in temperature. Release water vapor also impacts climate change since larger amounts increases the possibility of clouds and precipitation.

How Do Energy Efficient Buildings Help?

Large buildings require large amounts of energy to heat, cool, and operate. According to the Environmental and Energy Study Institute, buildings account for 39% of CO2  in the U.S.


Source: EEIA

The bigger reduction in a building’s energy use, the greater the reduction in GHG emissions; since less power translates to less power plants. Less power plants, means less GHG emissions from the burning of fossil fuels, not to mention nuclear plants which have their unique environmental concerns.

Cities Encouraging Energy Efficiency

More U.S. cities are taking steps to reduce energy use in their existing and new building stock. New York City recently passed the most aggressive municipal legislation on improving building energy efficiency. Other cities like San Francisco and Berkeley also have legislation with mandatory energy audit compliance rules to increase efficiency. San Francisco is also piloting a strategic energy assessment approach to encourage action.

How Do You Become More Energy Efficient?

One of the first steps to greater energy efficiency is an energy audit. There are different levels providing various levels of detail. Its critical to ensure you hire a good auditor to get the most value from your audit. Following through and implementing your audit recommendations is the essential key to realizing your energy savings and improving your efficiency.

Next Steps

Improving efficiency starts with knowing where you are. Start chatting with your facility staff about current operational issues, ask for help gathering your building equipment and energy use data, and any history about building projects. These will all be essential to your energy auditor. If you have any questions identifying energy saving opportunities in your building, contact us anytime.


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