Solar Gain

Solar gain is also known as passive solar gain and solar heat gain.  It is the process by which solar radiation increases the temperature in a space or building.  The amount of solar gain increases with the strength of the sun.

In the summer months when the sun is stronger, solar gain in the homes is greater.  Solar shading has been used to decrease the amount of solar gain in summer.  This reduces the need to cool the homes and therefore reduces energy demand.

In the winter months when the sun is weaker, solar gain in the homes is reduced.  Maximising solar gain reduces the need to heat the homes and therefore reduces energy demand.  The sun space has been added to the Code 6 home to maximise solar gain and create a 'greenhouse effect', adding warmth to the home.

Solar gain combined with high thermal mass (the ability of a material to store and release heat) greatly reduces the need for additional heating in the winter months.

Solar shading


Solar shading is a passive measure designed to reduce the risk of overheating which can occur in strong sun, especially during the summer. In this case, the roof has been extended to provide solar shading. This controls solar heat gain throughout the summer when the sun is higher in the sky. This helps maintain a more consistent internal temperature. The roof extension has been designed so that during the winter months, when the sun is lower in sky, the solar energy is let into the home. This helps to reduce energy requirements for heating.

How can the homes achieve warmth in the winter or remain cool in the summer?

Our strategy for capturing optimum solar energy via the solar thermal and PV panels is based on the predicted annual energy demand/generation. We anticipate that in the summer months that the PV will generate a large surplus that will be fed into the grid. Similarly we would expect that the solar thermal will provide all of the hot water demand or at least the majority. In the winter months, in particular January and February, the biomass boiler will be required for central heating and the hot water. Any solar benefit we get will be a bonus. The same is true for the PV although there will still be a contribution even on dull days.

The angle of the roof was chosen to accommodate the 22m2 of PV and also optimize solar access in the summer months.

The properties are being fitted with a range of monitoring equipment which will allow us to see what the actual power demand/generation actually is as both homes will be occupied. In many ways this is the more interesting part of the project as the build has been very simple and traditional and complying with the Code, whilst demanding, is design exercise. The monitoring will also investigate internal ambient conditions and water consumption/savings. Finding out how the properties, and the occupants, actually perform in practice compared to the theory will tell us a lot about the potential for housing to reach zero carbon.



See more information on thermal mass.

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Fact 23

77% of people know their home could be made more water efficient.
Source: Energy Saving Trust 2008