Roof Surface Temperature Calculation

Ts to a id is hso a absorption coefficient of outside surface id direct solar radiation on surface.

Roof surface temperature calculation.

For the calculation of surface temperature and heat flux the roof figure 1 was approximated by three homogeneous layers figure 2. 20 cm of cellular concrete. This calculator produced by lawrence berkeley national labs lbnl allows you to compute solar reflectance index sri and roof surface temperature based on solar reflectance and thermal emittance based on astm standard e 1980. You want a roof area calculator that provides accurate estimates to help you order materials such as shingles membrane roofing or ceramic tile.

The rooftop temperature results from two different properties. 7 cm dead air space ventilation and spacer blocks ignored 3. The ability of the material to reflect the sun s energy back into the atmosphere called solar reflectance and the amount of heat the material rejects instead of absorbs called thermal emittance both are measured on a scale from 0 to 1 with higher scores translating into cooler roofs. The house base area is the area of land that the house covers and for more complex shapes can be estimated using the area calculator.

To compute solar reflectance index sri and roof surface temperature based on solar reflectance r and thermal emittance e using astm standard e 1980. Your job is to calculate and illustrate the temperature gradient through a roof assembly composed of a gravel surfaced built up roof 3 4 inch thick perlite insulation 2 inch thick polyisocyanurate insulation two ply felt and asphalt membrane vapor retarder 1 2 inch thick gypsum board and metal deck. An approximate equation for the sol air temperature ts of the outside surface of a given wall or roof is. Area is defined as the expanse or measurement of a given surface and there are a few methods for measuring your roof s area.

7 5 cm of cellular concrete representing the top slab and the topping 2. The base width is the distance from one corner of your roof to the other at its base on the short side of your house. Ambient conditions and reference surface properties specified in next worksheet. Input r and e in blue and green cells.

1 roof square 100 square feet. Click on the red button to compute sri and roof surface temperature. The following tools estimate the area of a roof as well as the amount of materials necessary to construct a roof of a given area. Start the project with a roof area calculator.

The length l times the height h of a triangle is twice its area a2.