To get the most energy efficient building, facility managers often must evaluate trade-offs in strategies. The way to do that is with careful modeling and measuring of outcomes in terms of energy benefits. Here are some considerations when choosing energy efficiency projects.
1. Building façade
Buildings with fewer windows and better insulated concrete walls are more efficient than those with many larger windows. Solid and insulated walls do a better job of keeping internal temperature stable thus requiring less energy. This infrastructure is part of a building design which cannot be changed so is of little value when seeking to improve energy efficiency. Windows can be replaced with higher efficiency systems but may not make sense solely for energy efficiency and financial savings. Window replacement is usually put off until other factors make it a necessity. Roofs can be replaced, and then additional insulation can be added to improve energy efficiency as well. We now understand that the more airtight buildings are, while more energy efficient, will cause health problems. With the use of better ventilation and building façade technology and better energy monitoring, we can now accomplish energy efficiency without risking Sick Building Syndrome.
2. Plug loads
Total plug load use should be considered when considered total building energy efficiency. With increased occupancy, more people will be charging devices and using computers. This will increase the electrical consumption of the building. Facility managers should consider efficient power strips and other types of devices to help reduce plug load energy use.
3. Smart Meters, Lighting, HVAC
The most common approach to energy efficiency is to look at individual energy-using systems and determine how much can be saved by updating them. Where the cost of updating is less than savings over a measurable period, three to five years being typical, updating makes sense.
Smart metering systems allows facility managers to better understand and manage energy consumption. We now understand which changes make most sense for improving energy efficiency and cost reduction.
4. Measuring use
Even without system enhancements, the simple act of measuring and reporting electrical consumption yields savings of up to 30 percent without any decline in occupancy usage. The best results are achieved when occupants are aware of their own energy usage through direct billing or through an education program, showing energy usage in a public place.
Newer buildings are more efficient on a per square foot basis. Overall there are more computers, screens, appliances, and other equipment, all of which are more energy efficient but combined utilize more energy. Amenities, which improve the overall occupants comfort, are non existent or minimal in older buildings making comparisons less reliable. Newer buildings emit fewer greenhouse gasses because of modern technologies.
Ed Porasz, P.Eng. is vice president of MEP Growth Strategic Initiatives for M&E Consulting Engineers, a Rimkus Company. Rimkus AEC Services provides mechanical, electrical and life safety and energy efficiency consulting services for commercial and high-rise residential buildings.
