Roof Heat Loss

If there s too little ventilation the water vapor condenses resulting in decay timbers the corroding of metal fixtures felt injury and mildew growth.

Roof heat loss. Reduce power plant emissions including carbon dioxide sulfur dioxide nitrous oxides and mercury by reducing cooling energy use in buildings. An estimated 25 of all heat loss occurs through the attic or roof of a home. To outside air temperature. Reduce local air temperatures sometimes referred to as the urban heat island effect lower peak electricity demand which can help prevent power outages.

Q winter u a ti to ti inside air temperature. Once in the attic it warms the air over the living space. A typical 120 foot long roof edge with 6 12 overhangs and no gutters deicing will need about 291 feet of cable. Additionally improper ventilation in attics allows for much heat to escape.

That warm air makes contact with the roof deck and warms it up. If you have a light roof your home absorbs less heat through the roof during summertime. Because their ceiling isn t air sealed or insulated well enough to keep a lot of heat from escaping into the attic. That equals to 2 3kwh per hour or almost 56kwh per day of continuous operation.

With us average electric price of 0 13 kwh you will be spending 7 25 per day if your system is running full 24 hours. Total heat loss from the house 13 78 84 91 18 30 116 99 mmbtu in a year or heating requirement is 116 99 million btus per year. In contrast a dark roof likely raises the temperature inside your home s highest rooms. 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.

Heat loss from roof 2 750 ft 2 6 100 f days 24 h day 22 ft 2 f h btu 18 30 mmbtu. Consider that your entire house acts somewhat similar to a chimney. Heated air is distributed through your home and eventually rises to the top of the house which increases air pressure near the ceiling. In winter the heat loss is simple transmission based on the inside and outside temperature and u value of composite structure.

Warm air carrying high levels of water vapour is drawn by a method of convection to cold areas of the building as well as the roof void. That heat then conducts up all the way to the shingles. Roof and wall are analyzed in the same way. U value btu hr ft 2 o f w m 2 k wall area.

As a result your air conditioner operates more efficiently uses less energy and leads to lower utility bills. Composite wall r values up calculating wall heat loss example problems. Warm air escapes through your roof through the process of convection.