To save on your electric bill, you want to get lots of sunlight into your house. Your solar windows will act as solar collectors to get the heat in, but also as barriers to keep this warmth inside.

Solar windows are a vital element of a passive solar house design or of a zero energy house and should therefore be selected with great care.

Solar windows in a passive house are collecting solar heat, bring in light and ventilate your home.

Rule_1. Face most solar windows south.

The greater part of the house´s solar windows and patio doors should be facing south. This allows your house to take up the heat from the sun or allows you to ventilate with cool air when you need it. The amount of glass on the other walls (east, north, and west) should be more limited to get a better insulation from the winter frost and limit the heat gain in summertime. For an optimal passive solar house a larger part of your solar windows should be facing south. If you achieve this, you will get 25-90% of your heath requirement.

Rule_2. Beware of overglazing

Sometimes you will see some great houses with some huge sea facing solar windows. You would think, wow, those guys not only got themselves a great view, but also they can greatly use the sun´s warmth to heat up their house. Well, you probably right regarding their view, but many of those houses have too much glass for the amount of heat storage capabilities (thermal mass). This is known as overglazing and its leading to uncomfortably high temperatures. When this happens, you have to open your solar windows for the necessary ventilation, which is not only very uncomfortable in winter, but also limits the effective storage of heat which should be used when the sun is not warming up your room anymore.  A house with a south facing solar window area that is more than 20% of the total exterior wall area will face overheating problems.

Rule_3. Avoid angled solar windows

Avoid angled solar windows in a passive solar house design. Angled glass is not optimally placed to receive a low angled sun. This is a huge problem in winter. It is also very hard to insulate angled solar windows.

Rule_4. Keep the heat in

To keep the warmth in your house during the night and to keep controlling the amount of heat coming from the sun during the day, it is good to install insulated window curtains.

Solar windows are an essential element to get heat in and insulate your home well. Open up the south side of your house by placing sufficient solar windows, but do overdo it to run the problem of overglazing. Your payback period of these measures is excellent.