Roof Heat Loss Data

A cool roof is one that has been designed to reflect more sunlight and absorb less heat than a standard roof.

Roof heat loss data.

Q winter u a ti to ti inside air temperature. 1 0 net savings ft per year cooling savings ft per year heating savings heating penalty if negative ft per year insulation in black roof to yield same annual energy savings. In winter the heat loss is simple transmission based on the inside and outside temperature and u value of composite structure. In summer the solar radiation affects the outside surface of wall and roof.

U value btu hr ft 2 o f w m 2 k wall area. If the r value of walls and the roof is the same the sum of the areas of the walls and the roof can be used with a single r value. The overall heat transfer coefficient the u value describes how well a building element conducts heat or the rate of transfer of heat in watts or btu hr through one unit area m 2 or ft 2 of a structure divided by the difference in temperature across the structure. A green roof or rooftop garden is a vegetative layer grown on a rooftop.

When the winter chill sets in did you realize that you could be losing up to 25 percent of your home s heat through the roof. Total hourly rate of heat loss through walls roof glass is given by equation q u a t. To outside air temperature. Cool roofs can be made of a highly reflective type of paint a sheet covering or highly reflective tiles or shingles.

Online heat loss calculator. This energy is known as latent heat. Because green roofs store water in the growing media and plants latent heat loss is accomplished via transpiration from plants and evaporation of moisture from the growing medium collectively referred to as evapo transpiration. The heat loss in full heating season the heat loss from walls windows roof and flooring should be calculated separately because of different r values for each of these surfaces.

Using green roofs in cities or other built environments with limited vegetation can moderate the heat island effect particularly during the day. Nearly any type of building can benefit from a cool roof but consider the climate and other factors before deciding. Once you complete these easy steps you are sure to see increased savings in your energy bills. Green roofs provide shade remove heat from the air and reduce temperatures of the roof surface and surrounding air.

Roof and wall are analyzed in the same way. Thus your total cost when hiring a contractor will be 500 600. The average cost to install 100 feet of heat cable on the roof only is about 300 400 labor only excludes materials.