How Are Buildings Powered?
The most common energy sources used in commercial buildings are electricity and natural gas. The majority of individual commercial buildings have heating and cooling systems of their own. There are, however, district energy systems which supply groups of commercial buildings with heating and cooling. Having a central heating and cooling plant that distributes steam, hot water, or chilled water to several buildings is often more effective when several buildings are close together, such as on a college campus or in a community. District energy systems can also produce electricity along with heating and cooling energy. District energy systems generally use fossil fuels (coal, natural gas, or fuel oil), although some use renewable sources of energy (biomass, geothermal, solar, and wind energy).
At present, the vast majority of electricity used in buildings comes from fossil fuel supplies that are not renewable. The construction industry, on the other hand, also has the highest energy efficiency capacity. With increasing demand for fossil fuels coupled with uncertainty about the future availability of fossil fuels, growing energy security concerns (both for the general supply and specific needs of facilities), and the potential for greenhouse gas accumulation to cause undesirable impacts on the global climate, it is important to find ways to reduce load, increase efficiency and reuse.
During a building’s design and development, apply a comprehensive, integrated approach to the process, to:
- Reducing demand for heating, cooling, and lighting through passive strategies such as climate-responsive architecture, daylighting, and conservation practices;
- Specify effective HVAC and lighting systems that take into account part-load conditions and specifications for utility interfaces;
- Usage of renewable sources of electricity, such as solar hot water heating, photovoltaics, geothermal space heating and groundwater cooling, to minimize building loads;
- Optimizing construction efficiency through the use of energy modeling programs during design;
- Optimize device monitoring strategies through the use of service of occupancy sensors, CO2 sensors and other air quality alarms;
- Track the performance of projects by commissioning, metering, annual reporting and periodic re-commissioning policies;
- Consider retro commissioning of buildings that were never commissioned originally; and
- Integrate innovations for water saving to reduce the energy burden of the supply of potable water.
Electricity from the Power Company
At very high voltages, electric utilities transfer power most effectively from the power plant. Power utilities supply electricity to medium or large buildings at 13,800 volts in the U.S. (13.8kV). Power utilities lower the voltage with a transformer on a power pole or installed on the ground for small industrial buildings or residential customers. The electricity is fed from there via a meter and into the house.
Power Distribution in Small Buildings
A very simple power distribution system is available in small commercial or residential buildings. The transformer will be operated by the utility, and will sit outside the building on a pad or will be tied to a utility pole. The transformer lowers the voltage to 120/240 or 120/208 volts from 13.8kV and then transmits the energy to a meter that is owned by the utility and holds a power consumption record.
The power is transmitted into the building after leaving the meter, at which point all wiring, panels, and devices are the property of the owner of the building. The electricity from the meter is transferred by wires to a panel board, which is usually located in a house’s basement or garage. The panel may be located in a utility closet in small commercial buildings. The panel board will have a main service breaker and a series of circuit breakers, which control the flow of power to different circuits in the house. A device (some appliances need heavy loads) or a number of devices such as convenience outlets or lights will serve each branch circuit.