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The CEA Chronicle
Make Net Zero Happen in Utah
Large commercial buildings are often referred to as internal-load-dominated buildings due to a significant portion of their energy use, directly or indirectly, in response to the heat gains from internal loads, such as building occupants, lights, and electrical equipment. Implementing design strategies aimed at reducing and controlling these loads will result in decreased building loads, reduce energy expenditures, lower carbon emissions, and minimize the size and cost of HVAC equipment. Topics related to internal gains that should be assessed for any given project, include the following.
- Consider use of ENERGY STAR rated appliances and building products, wherever possible. ENERGY STAR, a joint venture between the EPA and the DOE, offers a rating to identify to energy efficient products, including appliances, building construction components, computers & electronics, HVAC & plumbing equipment, and lighting & fans. While ENERGY STAR rated products may be purchased at a higher price than standard equivalents, the cost difference is typically realized in energy cost savings, over the life of the product. More information is available at Energy Star.
- For mid-to-high rise commercial buildings, energy consumption related to elevators can be responsible for an appreciable portion of the building's energy consumption. For example, a six-story, downtown office building that is designed with four elevators can be equipped with well in excess of one hundred horse power worth of electric motor. Major elevator manufacturers offer product lines that have the ability to store the potential energy of a lowering elevator car, to be used toward the next raise of the elevator car which has been reported, in some cases, to offset up to 50% of the energy consumption related to vertical people conveyance.
- Reducing installed lighting power density and employing daylighting strategies can significantly reduce the internal loads associated with new construction and with renovation projects. More information regarding lighting systems and energy consumption can be found in the June 2010 edition of the CEA Chronicle.
- Building automation systems (BAS) can provide feedback and control of most building systems. Proper programming and periodic inspection of controls related to internal load systems, during unoccupied hours, can significantly reduce the run-time of equipment responsible for internal loads and reduce or eliminate unnecessary space conditioning by HVAC equipment. For example, if the BAS is properly controlled to turn off all unnecessary lighting overnight, the cost and energy consumption of the lighting system is held to a minimum and there is no additional cooling load that must be addressed by the HVAC system, beyond what is required for unoccupied set-back conditions.
- While credit cannot always be taken for occupant behavior in building rating system protocols, such as for LEED EAc1 energy modeling, occupant behavior can have significant impacts on the extent of internal loads and the energy consumption of the building. Education and awareness of building systems helps the occupants understand how their environment is being controlled and how they relate to those systems, thereby also reducing complaints related to human comfort. Good practices and reminders, such as to turn off computers and task lighting at night will contribute to reduced energy consumption and reduced energy cost to the owner, as well as extend the life of the equipment.
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