Last Updated on May 12, 2023 by Mary Pressler
How to Save Energy in an Office Building
Office buildings consume a lot of energy, and the way in which they use differs from the typical energy consumption of a household. Residential buildings have their highest consumption in the evening and early in the morning, since occupants are away the rest of the day, mostly working or studying. On the other hand, office buildings are more active during daytime, and their energy consumption is high precisely when residential consumption is reduced.
How Do Commercial Buildings Use Energy?
Electricity consumption in office buildings has several distinctive features. To use energy efficiency measures effectively, first we must understand where consumption is concentrated:
- To keep a suitable work environment, office buildings are strongly dependent on heating and cooling systems. While heating normally uses natural gas or other fossil fuels, air conditioning runs with electricity. On a hot summer day, air conditioning can represent over 50% of electricity consumption in offices.
- Offices involve plenty of management work, which requires suitable lighting and concentration for long hours. As a result, lighting fixtures normally represent between 20% and 30% of electricity usage in offices.
- Opening the windows is normally not enough to ventilate an office building, and doing so is impractical when heating or cooling systems are operating. As a result, offices depend on mechanical ventilation to supply fresh air.
This article describes 5 proven ways to save electricity in office buildings. However, note that every building is unique, and a professional energy consultant can discover additional savings opportunities.
1) Use a High-Efficiency Air Conditioning System
If an office building uses old window air conditioners in all rooms, power bills can be very high in summer months. Texas electricity rates are lower than in many other states, but air conditioning can cause high expenses nevertheless.
Since space cooling is the highest electricity expense during summer, it pays off to have a high-efficiency air conditioning system. The best solution changes depending on building conditions, but the following are some of the most efficient technologies in the market:
- Variable refrigerant flow systems, or VRF.
- Chilled water systems with smart compressors and cooling towers.
- For small offices, mini-split air conditioners with a high energy efficiency rating are recommended.
Although these systems are very different in their physical construction, they have a common feature: all of them optimize power consumption depending on cooling load, achieving savings of over 70% compared with window-type air conditioners. A professional HVAC engineer can determine the most suitable cooling system for your building.
2) Upgrade to LED Lighting
LED lighting upgrades are among the easiest and most cost-effective energy efficiency measures. There are many LED retrofit kits that can be installed in existing lighting fixtures, which minimizes cost and disruption.
Office buildings normally use fluorescent lighting for indoor areas, and HID lighting for outdoor locations such as parking lots. Consider the benefits of LED lighting:
- When replacing fluorescent lighting, LED products achieve savings between 30% and 50%, while lasting 2 to 3 times longer.
- When replacing HID lighting, LED products save over 50% and last 5 to 10 times longer.
Just make sure you are purchasing high-quality LED products. The best recommendation is looking for the ENERGY STAR label or the DesignLights Consortium (DLC) label.
Both labeling programs are similar, having stringent performance requirements. The difference is that ENERGY STAR focuses on residential lighting products, which often have commercial uses as well, while the DLC program focuses on commercial and industrial products.
3) Use a Smart Ventilation System
Offices rely on mechanical ventilation, as mentioned above, but there is no need to have fans at full power all the time. You can deploy a demand-controlled ventilation (DCV) system, which adjusts airflow according to the number of occupants. Fan speed is lowered when the full airflow is not required, and this achieves significant electricity savings.
An added benefit of DCV is a reduction of cooling expenses. Since there is less air flowing to indoor spaces when fan speed is reduced, the load on air conditioning equipment is lowered as well. The same principle applies during winter, reducing space heating loads and gas bills.
4) Make Sure All Motor Equipment Uses Efficient Motors
The National Electrical Manufacturers Association (NEMA) has developed a classification system for the most efficient motors in the market, called NEMA Premium Efficiency. When all the motors in a large office building are upgraded to NEMA Premium, it is possible to save thousands of dollars each year.
In office buildings, most motors are used in fans and pumping systems. Note that the NEMA Premium Efficiency rating is not available for motors smaller than one horsepower, but in that case you can use brushless direct-current motors. These are also known as electronically commutated motors (ECM), and they are the most efficient motors for small applications.
5) Improve Building Insulation and Airtightness
Even if you have the most efficient air conditioning system in the market, your office building will not achieve top performance if insulation is poor and air leaks are common. These deficiencies increase unwanted heat gain during summer, increasing the workload on space cooling systems. The opposite applies during winter, where poor insulation and air leaks cause a significant heat loss.
When your building has effective insulation and air leaks are minimized, the existing heating and cooling systems work more efficiently. Professional energy consultants can easily find trouble spots in your building insulation, as well as air leaks that are not evident for the untrained eye.
Office buildings consume large amounts of electricity to run their air conditioning systems, especially in the hottest days of summer, and lighting represents a significant expense during the entire year. By focusing on energy efficiency measures for these building systems, you can drastically reduce the power bills of an office building. To further boost the efficiency of air conditioning, make sure you have have adequate insulation and air sealing.
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