Factors That Affect Building Energy Use


Getting to Know Your Building: Part 1

from EngineeredSystems March 2015 issue

We spend a lot of our time in buildings, and they use a lot of energy. Since they are using energy for you (and everyone else in the building), we don’t want them to use any more than required to meet your needs! In this article we’re highlighting the factors that affect how much energy a building uses. We’ve found about a dozen factors, and will expand upon one that we think is important and is displayed on our energy dashboard. At the end, we’ll give you a few ways you can leverage these factors to save energy in your building.


The amount of energy a UC Davis building uses depends on:

  • How the building is used (laboratory, office, classroom, etc - see details below!)
  • The age of the building
  • The type of construction
  • Mechanical system type (and vintage)
  • Recent upgrades and maintenance on the mechanical equipment (especially the building’s control system)
  • Outside air temperatures
  • The occupancy of the building
  • The insulation of the building
  • Window type and shading
  • Heating, Ventilation and Air Conditioning (HVAC) Schedules
  • The sophistication of the temperature control system
  • Specialty equipment, e.g. lasers, MRI machines, etc.
  • The plug loads in the building


How the building is used impacts energy use.

Buildings can be used for a variety of functions: administrative offices, faculty offices, classrooms, laboratories for research and classes, food services, conference rooms, study areas and on and on.

Icons for Classroom, Lab, Community, and Office building types

We’ve grouped these uses into four types that we call classrooms, laboratories, community, and offices. Each type has an energy profile.

For example, offices, classrooms and community spaces generally use less energy compared to laboratories because some of the the air is recirculated throughout the building. The recirculation of air allows for less conditioning (heating and cooling) of the air and results in less energy being used.

On the other hand, buildings with lab spaces typically use a lot of energy because they often require much higher ventilation rates than an office, and the air cannot be recirculated. The air coming into a lab must be 100% outside air (not recirculated), and then it must completely leave the building through the exhaust systems. Moving this quantity of air with fans, and heating and cooling the air, is an energy intensive process.

As you can see, it's important to understand how a building is being used when looking at its energy use. You can look for your building on our energy dashboard– we encourage you to ponder the energy use in your space (and your coworkers spaces) and how it contributes to the whole building’s energy use.

our energy dashboard



Take the reins! Save energy in your building.

Some of the factors that affect energy use on our list above are building characteristics that can’t be changed, such as the type of constructionage of the building and outside air temperature. Factors such as the type of construction (e.g. concrete, brick, framed walls, etc), windows and insulation are affected by the California Energy Code, also called Title 24. The California Energy Code was created in 1978 and several newer versions have been released since then, each raising the bar for energy efficiency a little higher.

A few of the factors can increase the energy efficiency of a building, including upgrading the mechanical equipment, type of insulation, windows, and the sophistication of the temperature control system (thermostats and sensors). These types of changes can be very expensive though, so one low-cost measure we try to do is tune the building’s HVAC scheduling. You can help us tune the buildings’ HVAC schedules by using TherMOOstat to give us feedback on the temperature in your space.

Some factors are difficult to change because they affect the people in the building, such as the use of a building, its occupancy, and the need for specialty equipment. The last factor is the most important because this is where you can be the hero, plug loads. Plug loads include anything and everything plugged into the outlets in a building. Don’t forget about refrigerators, microwaves, and copy machines/printers. Some of our student interns have found that plug loads can be between 15-30% of a campus building’s energy use, so by doing what you can to save energy you can make a pretty big impact.

There are some easy things you can do to start making an impact:

1. Use TherMOOstat to give us feedback on the indoor temperatures.

The feedback you send using TherMOOstat feedback will help us create a comfort baseline and tune the building to suit occupants and save energy.

A TherMOOstat user submitting feedback

2. Investigate CEED

Look for your building on CEED, our energy dashboard and let us know if you’re interested in helping us figure out what percentage of the building’s energy use is plug loads. 


Screenshot of CEED


3. Go Plug Load Crazy

Explore your building’s plug loads yourself and streamline your personal space using power strips and power-saving modes. You can also team up with your coworkers to save energy in the communal spaces such as kitchens and conference areas.
If you or your department is ready to see how you’re doing in your energy saving practices, you can take the Green Leaf Assessment to earn a Green Leaf! How aware are you of energy waste in your space? Take our 4 step survey to find out how you can Trim the Waste!

A graph of electric plug load



Where do we get our info?
The Energy Feedback Team is conveniently positioned in the Energy Conservation Office. This gives us great access to three key sources of info: the energy manager of ECO, a staff member with over 17 years of experience working with campus buildings, and a team of energy engineers currently working to tune buildings on campus. Together, we work diligently to improve energy efficiency and comfort all around campus. 

Energy Optimization in Existing Buildings

– Abaza, M. Engineered Systems. BNP Media, 27 February 2015. Web. 26 April 2016.