# Heating and Insulating Buildings

Architects need to know how well different materials will insulate the building they design.  To help them with this they need to know the U-values of different materials.

A U-value of 1 W/(m2 oC) means a 1 metre square area of the material with a 1 oC temperature difference across the material will conduct heat at a rate of 1 joule per second.

U-values measure how effective an insulator something is. The lower the U-value the better the material is at insulating.

## Solar panels

These heat water using the energy from the Sun. The hot water provided can be used to heat homes or to provide domestic hot water.

photo by wonderlane

## Specific heat capacity

This is a measure of the amount of energy required to raise the temperature of 1kg of a material by one degree Celsius.

heat transfered    =            mass              x      specific heat capacity    x      temperature change

(joules, J)           (kilogram , kg)               ( joules / kilogram oC)              (degrees Celsius, oC)

Example; How much energy is needed to raise the temperature of 1 kg of water by 30 oC. The specific heat capacity of water is 4200 J/kgoC.