Studies suggest that residential energy use has increased during the pandemic. But it was not known what happens to the energy consumption in unoccupied buildings.
In recent decades, the booming global population, growing cities and climate change have drawn global attention to the need to build buildings that are energy efficient and sustainable… when in use. But what about unoccupied buildings?
In a recent paper, Farzam Kharvari and his colleagues at the Human-Building Interaction Lab found that empty buildings consume more energy than previously thought. The results were published in Building Simulation: An International Journal.
Why do unoccupied buildings use more energy?
Buildings use more energy when they are empty or partially occupied for long periods because they are designed to depend on human interactions.
The research found that empty buildings use more energy in colder climates because heating, ventilation and air conditioning (HVAC) systems must compensate for the heat typically generated by people’s daily activities.
A major reason behind the increase in energy consumption is the static programs that are used to design buildings. Static schedules provide an hourly estimate of the number of people who will occupy these buildings.
Although these programs are incorporated into the building design, they do not take into account the actual number of people or their movements in the buildings. As a result, buildings could not adapt to being empty during lockdowns.
Although research on replacing static schedules with stochastic schedules (schedules that take into account various factors and attributes, including but not limited to occupancy) is growing, research has shown that implementing simple strategies such as installing smart technologies can help buildings empty to accommodate partial occupancy, he notes Tech Xplore.
Technologies that can reduce this consumption
Technologies that sense the presence of people or count occupants can help mitigate the negative impact of static schedules.
The simplest technology widely used in offices is occupancy sensors for lighting. A wide variety of products that control lighting in buildings, from simple automatic switches to dimmable smart lights, are readily available today. They mainly work with a simple indoor motion detection device that controls the lighting and are able to save electricity effectively.
Smart plugs can also reduce electricity consumption. Smart plugs allow you to control your devices remotely. But more importantly, they can be used to control devices that use electricity when they are on standby and have the potential to reduce electricity consumption for equipment.
What could be used in unoccupied buildings in colder climates?
Another technology used in buildings is demand-controlled ventilation (DCV), which helps control airflow and adjust the ventilation of HVAC systems based on occupancy. Research has shown that DCV is able to save energy significantly, especially in colder climates, because the HVAC system has to heat less outside air for indoor spaces during partial occupancy.
Lowering the thermostat setpoint in empty spaces has also been shown to have a significant impact on energy savings in offices, as HVAC systems heat the space to a lower temperature.
The advent of smart thermostats can drive more energy savings in unoccupied buildings. Dedicated thermostats for different spaces in a building not only result in energy savings, but also provide greater thermal comfort.
The solutions are varied because they depend on many factors
While the use of smart technology can help buildings adapt to partial occupancy, taking this partial occupancy into account during the design phase can maximize the building’s potential energy savings. For example, multi-story offices may consider moving all employees to one side or one floor during partial occupancy.
Whether you’re thinking of buying a smart thermostat or smart plugs for the office, new technology can be quite expensive.
Therefore, it is important to start equipping buildings with solutions that encourage optimal energy and money savings. These possible savings can vary depending on climate, building type and many other factors.
Assessing each building individually to see the performance of different technologies and strategies can help sustain buildings in the absence of human interactions or during periods of partial occupancy. This, in turn, will help reduce emissions and strengthen the fight against climate change.