Passive Solar Design and the Passive House
South facing windows are beneficial in the winter since the sun will shine straight in, even at midday. In the summer, however, there could be a lot of over heating. This is easily taken care of by adding a trellis over south facing windows or larger eave overhangs. Summertime overheating and heat storage in the winter can be facilitated using high thermal mass materials like concrete. It makes for an amazingly simple floor that looks great when polished.
Concrete has a large thermal mass. it can absorb heat, redistribute it, and it will continue to release that heat into the evening. In the summer, that same thermal mass serves to help keep the inside of the house at a constant temperature.
Careful placement of windows are very important. In the summer, the sun rises quickly in the East and since the suns rays pass through less atmosphere then in the winter, the sun's energy starts to warm the east side of the house early in the day. This will lead to overheating later in the day. In addition, west facing windows will continue to heat the house late into the day when the house is already warm leading to overheating. So minimizing the size and amount of windows on the east and west of the building will make for a more comfortable house year round. To the north, the house is always in a shadow. The light through north facing windows is great but they will act as an energy sink in the winter. Minimizing the number and size is obviously important to a good design.
Finding a lot is part of the battle for a good design....especially for passive solar. A lot with good southern coverage will maximize solar gains if the home is oriented towards the south as shown in the picture below. However, orienting the home up to 22 degrees away from south will still allow for about 92% gains. This is still pretty impressive. However in the summer, the west setting sun will lead to excess heat in the home unless some shading control is added to block the summer sun. Passive House design is is flexible. As long as there is some south facing wall of the building, a Passive House design is still possible. Architects and designers have some great ideas about how to achieve this and still maintain the look and feel of a building so it doesn't look like a space ship!