What is Roof Temperature?
Roof temperature is the estimated surface temperature of a roof based on the outside air temperature plus solar heat gain. Roofs absorb sunlight and radiate heat, making their surface significantly warmer than the surrounding air. Knowing the roof temperature helps with planning roofing work, evaluating insulation performance, and estimating cooling loads.
How to Calculate Roof Temperature
Here is the formula for Fahrenheit:
[\text{RT} = \text{OAT} + 25]
And for Celsius:
[\text{RT} = \text{OAT} + 13.89]
Where:
- RT is the estimated roof temperature.
- OAT is the outside air temperature.
- 25 (or 13.89) is the standard solar heat gain offset.
Calculation Example
The outside air temperature is 85 °F.
[\text{RT} = 85 + 25 = 110]
The estimated roof temperature is 110 °F.
In Celsius, if the air temperature is 29.4 °C:
[\text{RT} = 29.4 + 13.89 = 43.29]
The estimated roof temperature is approximately 43.3 °C.