What Consumes The Most Energy In A Commercial Building?
Lighting and HVAC are the main energy consumers in the average commercial house (Heating, Ventilation and Air Conditioning). In most medium to large commercial buildings, electricity rates cover both demand and supply charges, but many energy cost management techniques concentrate on consumption and ignore the much greater savings arising from peak demand regulation in order to lower demand charges. The aim of this article is to show building owners how to use data from a “smart meter” utility or a power metering solution to identify and estimate the potential benefit of Demand Control in their own buildings. In many cases a Building Automation System that controls HVAC and lighting to manage both electrical consumption and demand can deliver substantial, consistent savings while maintaining building comfort and productivity.
Understanding Energy Costs
For an efficient building environment, heating, ventilation, and air conditioning (HVAC) and lighting are all necessary and are the two key areas where energy is usually used in commercial buildings. Industrial facilities, such as office buildings, hospitals, retail stores, warehouses, medical suites, and the like, use approximately 19% of the electricity used in the United States, so a whole lot of energy is used for lighting and HVAC.
Depending on the types of mechanical equipment and lighting in place, prevailing climate, timing of use, comfort preferences, construction age, windows, insulation, and other site-specific factors, how much energy the lights and HVAC in your own building use can vary.
Many commercial buildings have an electricity rate plan or tariff that includes charges for demand (capacity) as well as charges for energy (consumption). Production is measured in kilowatts (kW), or thousands of watts, and the consumption of energy is measured in kilowatt-hours (kWh). A 1,000 watt electric heater generates 1 kW of demand and absorbs 1 kWh if left on for 1 hour. Demand costs are not included in residential bills as a rule.
There is also an option for clients as to which tariff they are on. Many utilities will have a cost comparison to tell you how high your bill will be on an alternative tariff, either on your bill, through a web page, or to your utility account representative upon request. Several consumers are shocked to discover that they can save money simply by swapping tariffs; a customer’s best tariff would depend on their individual usage profile.
For those customers with a high load factor, such as the ratio of average kW to peak kW, the demand charges in a tariff may be of benefit. By converting from the non-demand metered General Service tariff to the demand-metered Broad General Service tariff, we recently reported $40,000 (22 percent) in annual savings for a senior housing complex in Tucson, AZ. We identified how an EMS system, combined with a 50 kW solar array, would enable private high schools to move from E32-L to E32-M in the nearby APS service area and dramatically reduce energy costs. The senior facility has a high peak load factor, while the high school has a low load factor, so that each has a different optimum demand and usage charge balance.
