Pros and Cons of Direct Gain Passive Solar Homes

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Direct gain passive solar homes have many advantages and disadvantages compared to other approaches. Historically, the first direct gain homes were often a complete mess, because the designers had little understanding of the need to balance things like solar glazing and thermal mass. Modern designs are much better, especially since analysis software is now available to help make the tough decisions.

The advantages

  • Direct gain passive solar homes are the easiest to implement.
  • The basic approach is extremely simple: orient south, add windows, insulate and tweak.
  • The gains in comfort and heating cost reduction are immediate.
  • The designs have low environmental impact, especially if the greenest materials are used.
  • The direct gain requirements fit well into a multitude of architectural styles.
  • Direct gain passive solar homes are aesthetically pleasing.
  • Solar glazing can go on the front, sides or back of the house, whichever faces the sun.
  • Passive solar homes tend to have light, airy interiors which are bright and cheerful.
  • Direct gain designs get a lot of daylighting, reducing electrical bills and giving a pleasant living and working environment.
  • Direct gain homes with open plan designs can be smaller than traditional houses.
  • The extra solar glazing often gives exceptional views of natural beauty.
  • The reduced air infiltration in passive solar homes means they are never drafty.
  • With appropriate thermal mass, solar homes are comfortable and warm, maintaining stable temperatures throughout the year with little additional heating.


The disadvantages

  • Direct gain passive solar home designs are the easiest to completely mess up.
  • The basic approach hides a lot of complexities and a great deal of careful balancing – there's a lot you can get very wrong, very easily.
  • Overglazing causes the home to overheat.
  • Too little thermal mass also causes the home to overheat.
  • Too much solar glazing can make the home very cold at night and on cloudy days.
  • All the extra daylighting can cause serious glare issues unless care is taken to create sun-free zones.
  • The extra light can also cause furnishings to fade, though modern advances in UV protection reduce the effect.
  • The large amount of solar glazing can give rise to privacy problems unless the windows are carefully shaded.
  • The solar glazing can turn into a heat sink if it is not properly insulated, or if the insulated shutters are a hassle to operate every night.
  • House plants – particularly tropicals – can suffer badly with too much sun in winter and not enough light in summer.