Strategies to Reduce Energy Use in Energy Intensive Buildings

Photo by Doris Morgan on Unsplash

By Ali Karim-Lee

Moving towards achieving a sustainable future, reducing energy consumption is a crucial part of the process. Residential and commercial buildings account for about 28% of total U.S. end-use energy consumption in 2021 according to U.S. Energy Information Administration.

With respect to energy, buildings can be categorized by the metric of Energy Use Intensity (EUI). EUI indicates the total energy consumption of a building in one year relative to the total gross floor area of the building. While EUI varies considerably for different building types, it can be used as a benchmarking tool to compare energy performance of buildings with similar type and function. Certain building types will use more energy and be classified as energy intensive buildings. Examples of such buildings include healthcare facilities with EUIs in the range of 200 kBtu/ft2 and above and restaurants with EUIs of about 300 kBtu/ft2 and above.

The dominant portion of energy use in energy intensive buildings are associated with process loads accounting for industry-specific equipment. Improvements to reduce such equipment energy use are mostly beyond the scope of the buildings sector and falls under the energy efficiency in the industry sector.

From building design and operation perspective and considering Energy = Power x Time, improvements to reduce process energy use are limited to the Time component of energy use as reducing Power of process equipment is not always feasible. In commercial and residential buildings, many power reduction opportunities can be attained by load reduction and using efficient HVAC systems, lighting, service water heating systems and appliances, while industry-specific process equipment can be within limited market/design options. With this regard, process energy use reduction approaches will be more focused on schedules and controls of process equipment. By identifying and understanding different process loads for each of the space types within the energy intensive buildings, appropriate strategies can be adopted to reduce energy use within each space type. Moreover, industrial processes can provide opportunities to harvest the generated waste heat during processes. One strategy for waste heat recovery is to use a coil in the exhaust stream to harvest heat.

Another aspect of energy use in energy intensive buildings such as laboratories and testing facilities is the ventilation requirements. By adopting a space demand control ventilation approach, ventilation can be adjusted to meet the air quality requirement based on continuous air quality monitoring and therefore over-ventilations will be prevented.

Dual lighting and HVAC occupancy sensors help reduce energy by dimming the lights and reducing the HVAC airflow while occupants are not present in each space within the facilities with varying occupancy patterns. Another significant energy use can be due to fume hoods in space types such as educational labs and food service. Fume hood occupancy-based sensors can limit hoods operation to times when required only.

The above-mentioned strategies are around the schedule and control of end-use while in energy intensive buildings, processes and building operational demands are substantial fractions of buildings energy use.

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