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When concrete is subject to an excessive temperature increase during its setting and hardening as in massive concrete structures from where cement hydration heat cannot easily escape (semi-adiabatic conditions), the temperature gradients and the differential volume changes can also cause the formation of thermal cracks and fissures.
The ground floor with a slab on grade has less temperature rise compared to middle and top floors, and an increase of the supply air temperature causes a decrease in the temperature rise. The temperature rise is not significantly affected by the perimeter zone orientation, the internal heat gain and the window-to-wall ratio. [ 16 ]
Because axial fans are designed to blow air straight down at the floor, they can be used in ceiling and roof structures over 100 ft. tall. Because axial destratification fans can achieve destratification with low CFMs, it is imperative that the air leaving the nozzle achieve an air speed at the floor of between 0.2 and 0.5 m/s.
Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]
construction site workers loading water, sand, ballast and cement into a concrete mixer. Concrete is typically used in commercial buildings and civil engineering projects, for its strength and durability. Concrete is a mix of cement and water plus an aggregate such as sand or stone. Its compression strength means it can support heavy weights. [5]
Under floor radiant systems are evaluated for sustainability through the principles of efficiency, entropy, exergy [33] and efficacy. When combined with high-performance buildings, underfloor systems operate with low temperatures in heating and high temperatures in cooling [34] in the ranges found typically in geothermal [35] and solar thermal ...
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The building balance point temperature is the outdoor air temperature when the heat gains of the building are equal to the heat losses. [1] Internal heat sources due to electric lighting, mechanical equipment, body heat, and solar radiation may offset the need for additional heating although the outdoor temperature may be below the thermostat set-point temperature.