LEVEL 7

How Do We Save Energy on Campus?

Adjusting Cooling Setpoints

In Level 6, we talked about how campus HVAC systems work. When an HVAC system has to cool a building or zone to 72°F, the cooling system will be running almost continuously. If the setpoint is raised from 72°F to 75°F, the indoor temperature will be a little warmer, but the HVAC system won’t have to work as hard or continuously cool the building.

 

Even more energy savings are possible when the setpoints change according to occupancy, called an unoccupied setback. Energy can be saved when spaces are not actively cooling when no one is there.

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Matching Building Occupancy

Historically, HVAC schedules on campus were set to avoid complaints from occupants - which often meant that systems would run late into the nights and on weekends. To reduce the energy wasted by conditioning empty spaces, our team is working with individual buildings to match HVAC schedules to the actual occupancy patterns and provide flexibility to after-hours occupants through local buttons.

 

Scheduling the HVAC systems is a great strategy for office, classroom, and community buildings. These buildings have similar heating and cooling needs and their patterns of occupancy lend themselves to turning down at night, on weekends, during national holidays, and also during intersession periods.

What Would These Energy Savings Look Like?

Matching the HVAC system to building occupancy means not cooling the building after the building is empty. For example, taper cooling starting at 6pm instead of 9pm when possible.

 

Another opportunity to save cooling energy is to use less cooling in the morning, when it’s typically cooler outside. This conservation strategy is called economizing.

The heating of buildings should also take into account the occupancy of the building. If people arrive at 8am, the heating may need to start around 6am or 7am for the building to be a comfortable temperature at 8am. 

 

Heating in the warm afternoon is likely due to the overcooling of some spaces, leaving other spaces to be re-warmed. Simultaneous heating and cooling is a sign of energy waste.

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Hover to see the potential savings!

The highlighted blue areas represent 

the possible energy savings.

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Hover to see the potential savings!

The highlighted orange areas represent the possible energy savings.

Diving into Building Energy

Did you notice a building type that wasn’t mentioned above? If you’re thinking “lab buildings”, you’re right. Lab buildings have different requirements compared to other building types, such as constant ventilation, a stricter range of temperatures, and unique use of space. Therefore, scheduling HVAC systems doesn’t work as well for lab buildings. However, lab buildings are the target for the second energy-saving strategy, deep dives into building energy. These deep dives take months of research, analysis, and planning by our energy engineers.

 

The implementation of these projects also takes time and coordination. In a deep dive, there are Energy Conservation Measures that add up to a lot of building energy savings. These can include:

  • scheduling the HVAC system to match occupancy

  • adjusting the heating and cooling setpoints for energy efficiency and occupant comfort

  • programming hot water and chilled water systems

  • building-level improvements via equipment upgrades or addressing operational issues (air handlers, exhaust fans, etc.) 

Typically, these measures take place on a large scale, fine-tuning the performance of an air handler which affects several rooms and floors. The result is building projects that save thousands of dollars in energy savings. These building projects start saving energy during implementation and continue to generate energy savings for years to come. Calculating these energy savings also takes a deep dive into the building’s energy data. This data is used to create a model of what the energy use would look like in the future if the project were not implemented. The energy use after the project and the estimated energy use without the project are compared to find the project's energy savings.

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NEXT: What Factors Affect Energy Savings?