Synopsis: Reducing operational energy use in buildings helps when trying to lower greenhouse gas emissions. From passive design strategies to installing solar panels there are several ways to promote energy efficiency in a building.
Reducing Operational Energy Use in Buildings
Many people do not realize how much energy it takes to keep a building running. In 2018, 20% of the global energy consumption was used in the building sector (which includes residential, and commercial). In addition to this large percentage, the US Energy Information Administration (EIA) predicts that energy consumption in buildings will increase by 1.3%-2%, on average, per year from 2018 to 2050.
As a result, our environment takes a hit. In 2018, almost 40% of greenhouse gas emissions were from buildings. Of that 40%, building operations accounted for 28%. That means almost three quarters of a building’s emissions come from simply using the building. According to the Climate Technology Centre & Network (CTCN), there are three main ways to lower operational energy in the attempt to make a building more sustainable and energy efficient.
1. Reduce the Need for Energy Use
The easiest way to reduce a building’s operational energy is to use passive design strategies. These are aspects of the building itself and require no energy after construction.
The first thing to consider is the orientation of the site and how the building will be situated on it. Identifying the cardinal directions will help determine where windows should go and the overall interior plan. Windows should face the south as the sun shines more in that direction; the sun’s natural heat will warm the area it shines upon, reducing the amount of additional heating needed. When thinking about the interior, having a living room with south facing windows is ideal since this is a frequently visited area. The sun is your best friend when it comes to reducing heating loads.
Analysis of the sun is once again helpful in reducing the amount of cooling. Knowing what areas of the building will be shaded already by surrounding trees and structures is crucial. You don’t want to be spending money on shading devices for areas that will already be shaded. For places that are not covered, shading devices can be implemented in the design. These are coverings on top, around, or even over a window. A solar analysis is also necessary as the sun is higher in the sky in the summer than it is in the winter. With this, it is possible to calculate the length of overhang that is able to shade the sun in the summer, when heat is unwanted, and allow the sun to enter in the winter, when you want to heat the area.
Choosing the best material to build is also important. Thermal mass is the ability of certain building materials to absorb, store and release heat. Materials like concrete, and tile can absorb heat, typically from the sun, and then release it when the surrounding temperature drops below that of the material. This can help with cooling in the summer as well as heating in the winter.
Cross ventilation is also a huge aid in the summer when the focus is on cooling the building. Operable windows on opposite sides of rooms can allow air to pass through the room and create a breeze. Windows that can open and placed higher up on a wall are perfect for letting heat escape during the summer as well.
It seems obvious but another way to reduce energy loads is by using the light from windows as a way to illuminate areas. Having sufficient windows in a building can reduce lighting during the day. As well, windows that are higher up and possibly shaded by an overhang can provide diffused light that does not produce a glare.
A big part of reducing the amount of energy needed is designing a durable and efficient building envelope. The building envelope is designed to keep the outside out and the inside in. Good insulation, vapour control and airtightness are necessary. Continuous insulation, with no thermal bridges, is a good way to keep the hot or cold air inside a building when needed. By doing so, you do not waste energy heating or cooling the building more than necessary. When calculating how much insulation is needed, it is always a good idea to aim higher than the building code. In addition, good windows are very important because the most energy is lost through the windows.
Passive measures implemented in a building design could change depending on what climate zone the building is in and what the uses of the building are.
2. Minimize Energy Required to Meet Needs
The next best way to reduce a building’s operational energy is to minimize energy usage in general. We use energy for many reasons but it is important to be aware of how much energy certain actions take and ways on how to keep them to a minimum.
HVAC systems take up a lot of a building’s energy usage so it is necessary to have an efficient arrangement. Other than just having an energy saving system, there are a few other things that you want to make sure of. The series of ducts hooked up to your building cannot be leaky. If they are, that allows the air to escape before it reaches the intended area. You also want to make sure that you keep your HVAC clean from dust and dirt. Changing the air filters frequently can help with this. Other ways that help your HVAC run efficiently include having regular maintenance, cleaning your drain line and having the appropriate sized HVAC system and ducts.
In addition to efficient HVAC systems, efficient appliances, such as washer/dryer, and fridge, are important in minimizing energy usage. Efficient light bulbs, like LEDs, can help to reduce the energy needed to light up the space.
Having an automatic thermostat that can turn down your heat at night is also a big help in reducing energy usage. Setting your thermostat down to 16 degrees from 21 degrees can save up to 10% of your energy used for heating. Additionally, if you are cold, instead of turning up your heat you can put on a sweater or blanket.
3. Generate Energy With Renewables
Buildings obviously need energy. There is no way to eliminate energy use in its entirety. However, it is best to use renewable energy whenever possible.
Solar panels are a good use of renewables in buildings. They are usually installed on roofs and face south for optimal solar access. When using solar panels, it is better to be connected to the electrical grid instead of using a battery as batteries at the end of their lifespan end up in landfills. Connecting to the electrical grid can ensure that you will still have power in the evening or when the sun isn’t out. Additionally, if you generate more electricity than you use, that electricity can be sold back to the grid.
Another exciting renewable energy source that can be used in a building is geothermal heating and cooling. When looking at geothermal for buildings, a ground-source heat pump (GSHP) would be used. A GSHP uses a mix of water and antifreeze that passes through pipes that run 90m to 160m into the ground. The heat from the earth is absorbed into the mixture and then goes through a heat exchanger and heat pump, which is transferred into the building. GSHPs can make HVAC systems smaller as they combine the heating and cooling into one piece of equipment. Geothermal heating and cooling is usually preferable to air-source heat pumps as the temperature of the earth is far more stable than that of the air.
When trying to reduce the operational energy consumption of a building, using these strategies can assist substantially and we can start to make buildings more sustainable. Reducing the need for energy use, minimizing the energy required, and generating energy with renewables will lower our greenhouse gas emissions and have huge benefits now and for future generations!