Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR.
In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy, in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices.
In architecture, a cornice is generally any horizontal decorative moulding that crowns a building or furniture element—for example, the cornice over a door or window, around the top edge of a pedestal, or along the top of an interior wall. A simple cornice may be formed just with a crown, as in crown moulding atop an interior wall or above kitchen cabinets or a bookcase.
A radiant barrier is a type of building material that reflects thermal radiation and reduces heat transfer. Because thermal energy is also transferred by conduction and convection, in addition to radiation, radiant barriers are often supplemented with thermal insulation that slows down heat transfer by conduction or convection.
A solar chimney – often referred to as a thermal chimney – is a way of improving the natural ventilation of buildings by using convection of air heated by passive solar energy. A simple description of a solar chimney is that of a vertical shaft utilizing solar energy to enhance the natural stack ventilation through a building.
A kitchen hood, exhaust hood, hood fan, extractor hood, or range hood is a device containing a mechanical fan that hangs above the stove or cooktop in the kitchen. It removes airborne grease, combustion products, fumes, smoke, heat, and steam from the air by evacuation of the air and filtration. In commercial kitchens exhaust hoods are often used in combination with fire suppression devices so that fumes from a grease fire are properly vented and the fire is put out quickly. Commercial vent hoods may also be combined with a fresh air fan that draws in exterior air, circulating it with the cooking fumes, which is then drawn out by the hood.
A mechanical floor, mechanical penthouse, mechanical layer or mechanical level is a story of a high-rise building that is dedicated to mechanical and electronics equipment. "Mechanical" is the most commonly used term, but words such as utility, technical, service, and plant are also used. They are present in all tall buildings including the world's tallest skyscrapers with significant structural, mechanical and aesthetics concerns.
Roof shingles are a roof covering consisting of individual overlapping elements. These elements are typically flat, rectangular shapes laid in courses from the bottom edge of the roof up, with each successive course overlapping the joints below. Shingles are held by the roof rafters and are made of various materials such as wood, slate, flagstone, metal, plastic, and composite materials such as fibre cement and asphalt shingles. Ceramic roof tiles, which still dominate in Europe and some parts of Asia, are still usually called tiles. Roof shingles may deteriorate faster and need to repel more water than wall shingles. They are a very common roofing material in the United States.
An attic is a space found directly below the pitched roof of a house or other building; an attic may also be called a sky parlor or a garret. Because attics fill the space between the ceiling of the top floor of a building and the slanted roof, they are known for being awkwardly shaped spaces with difficult-to-reach corners and often exposed rafters.
Radon mitigation is any process used to reduce radon gas concentrations in the breathing zones of occupied buildings, or radon from water supplies. Radon is a significant contributor to environmental radioactivity and can cause serious health problems such as lung cancer.
Ventilation is a part of structural firefighting tactics, and involves the expulsion of heat and smoke from a burning building, permitting the firefighters to more easily and safely find trapped individuals and attack the fire. If a large fire is not properly ventilated, it is much harder to fight, and can build up enough poorly burned smoke to create a smoke explosion or enough heat to create a flashover. Poorly placed or timed ventilation can increase the fire's air supply, causing it to grow and spread rapidly. Flashover from inadequate ventilation can cause the temperature inside the building to peak at over 1,000 °C (1,830 °F).
Domestic roof construction is the framing and roof covering which is found on most detached houses in cold and temperate climates. Such roofs are built with mostly timber, take a number of different shapes, and are covered with a variety of materials.
An asphalt shingle is a type of wall or roof shingle that uses asphalt for waterproofing. It is one of the most widely used roofing covers in North America because it has a relatively inexpensive up-front cost and is fairly simple to install.
Passive ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces.
A powered attic ventilator, or attic fan, is a ventilation fan that regulates the heat level of a building's attic by exhausting hot air. A thermostat is used to automatically turn the fan off and on, while sometimes a manual switch is used. An attic fan can be gable mounted or roof mounted. Additional vents are required to draw in the fresh air as the hot air is exhausted. Attic fans are typically used in warmer months, when temperatures in an attic can exceed 120 °F (49 °C). A fan may be installed in an attic for the different purpose of cooling a whole house, venting hot air out via the attic; such fans are often called whole-house fans.
Air changes per hour, abbreviated ACPH or ACH, or air change rate is the number of times that the total air volume in a room or space is completely removed and replaced in an hour. If the air in the space is either uniform or perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced each hour. Perfectly mixed air refers to a theoretical condition where supply air is instantly and uniformly mixed with the air already present in a space, so that conditions such as age of air and concentration of pollutants are spatially uniform.
Benjamin Obdyke Incorporated is a building materials manufacturer based in the Philadelphia suburb of Horsham, Pennsylvania. The company was started by its namesake, Benjamin P. Obdyke in 1868. Benjamin P. Obdyke is credited with creating and manufacturing the first corrugated downspout while the company itself claims patents on three products that have been integral in the advancement of building practices over the past 20 years: Roll Vent the first rolled ridge vent, Cedar Breather the first wood roofing underlayment, and Home Slicker the first rolled product to provide drainage and air flow in rainscreen wall assemblies. While the company’s origins are closely tied to the metal gutters and downspouts business, Benjamin Obdyke sold off that part of their business in the late nineties and now exclusively sells roof and wall products that help improve the building envelope, most of which feature the company’s patented matrix technology.
The Roosevelt Point Cottage and Boathouse are located on the Hudson River near the end of River Point Road in Hyde Park, New York, United States. They were both built around 1860 as part of Rosedale, the estate of Isaac Roosevelt, grandfather of Franklin D. Roosevelt.
A solar fan is a mechanical fan powered by solar panels. The solar panels are either mounted on the device or are installed independently. Solar fans mostly do not require secondary power sources other than solar power, as most of them are used for cooling purposes during day time. Some types are also used for heating purposes. It runs the fastest when it is the hottest outside providing savings on air conditioning costs.
A skylight is a light-permitting structure or window, usually made of transparent or translucent glass, that forms all or part of the roof space of a building for daylighting and ventilation purposes.
