A fourth discipline, Controls, pervades the entire HVAC field. The term HVAC refers to the three disciplines of Heating, Ventilating, and Air-Conditioning. The integrated design process can provide the means to facilitate early consideration of wind loading, vibration, blast and seismic considerations pertaining to rooftop HVAC equipment. There are also considerable opportunities for significant energy savings through efficient, integrated design, especially at the building envelope.Īn integrated and efficient building envelope with appropriate window and glazing design can not only reduce the energy and operating costs of a facility, but can also reduce the size and cost of the HVAC system needed to maintain adequate building pressurization, good indoor air quality and a comfortable thermal environment for building occupants.Īn often overlooked component of the building envelope is the relationship of the roofing system with the large HVAC equipment that is often mounted on the roof. Consequently, almost any business or government agency has the potential to realize significant savings by improving its control of HVAC operations and improving the efficiency of the system it uses. The following links provide more detailed information on building envelope components and the minimum thermal requirements of envelopes for different climates as defined by ASHRAE.Heating, ventilating, and air-conditioning (HVAC) systems account for nearly 40% of the energy used in commercial buildings in the United States. These complexities must be considered by a designer who intends to deliver comfort and energy efficiency. The flow of heat through a building envelope varies both by season (heat always flows from hot to cold and generally flows from a building in winter and to a building in summer) and by the path of the heat (through the materials of a building’s skin, or by outdoor air entering). When external conditions are very close to the desired internal ones, the envelope often begins as an open structural frame, with pieces of the building skin selectively added to modify only a few outdoor forces. This may also be true where there are unwanted external influences such as noise or visual clutter. In harsh climates, the designer frequently conceives the building envelope as a closed shell and proceeds to selectively punch holes in it to make limited and special contact with the outdoors. The range of choices in envelope design can be illustrated by two opposite design concepts: the open frame and the closed shell. The choice of envelope is governed by the climate, culture, and available materials. ![]() The envelope may be composed of membranes, sheets, blocks and preassembled components. ![]() Extra insulation retains heat in winter, but operable windows passively cool it in summer.įrom an energy flow perspective, the envelope is a composition of layers with varying thermal and permeability properties. ![]() It also uses a light roof and darker walls to repel summer sun but absorb winter sun. Flexibility is the key to designing for these climates. The Aldo Leopold Center in Wisconsin, the first building to be LEED certified as carbon-neutral, uses deep overhangs to allow low winter sun in through the windows to heat up a high-mass concrete slab inside, while blocking high summer sun. Many “temperate” inland climates actually have two extremes-cold in winter, hot and humid in summer. ![]() The Aldo Leopold Center in Baraboo, Wisconsin.
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