Getting Light Into The House Safely

A window is an important element in the building envelope. As with insulation, the greater the difference in temperature between the outside and the inside of a house, the better the windows will have to be. Look carefully to see the relative performance of the windows that are used in the different case study buildings around the world. For details of different windows there are a number of excellent sites on the Internet, listed under 'window performance'. The key things with window design are:

• To ensure windows are similar in thermal performance to the adjacent walls so they do not become too attractive to condensation.

• In temperate or colder climates, the side of the building facing the sun should have more windows and the polar orientation

The TDR for a concrete floor slab both with and without fins or balconies. The cavity wall is 105 mm brick-50 mm cavity-105 mm brick, the solid wall is 260 mm brick, the floor is 150 mm dense cast concrete and the insulation is 25 mm drylining or external.

very few to prevent excessive heat loss from the cold side of the building.

• To design the window for a specific purpose. Look at Dick Levine's case study house in Kentucky where he has separate windows for solar gain, light, wind and view.

• To illuminate the centre of the house as well as its peripheral rooms. This can be done with internal windows, skylights, light tubes through the roof and other clever ideas. One idea that was very popular in the 1930s was to use glass ceilings in the upper floor that took the light from the sunny side of the building to the ceilings on the dark side of the house, often above stair wells.

• To not make unshaded windows too large. It is important to prevent overheating in a house. With global warming the sun will get stronger and rooms that are exposed to the direct sun in summer will have a problem. Shade all windows in summer. Only in the colder climates should the sun be allowed to penetrate into the house in summer. It is very important to design for solar control through windows but also in their external surroundings. Take into account highly reflective pavements outside the window that will bounce light back into a room, as will glass walls next to or opposite the window.

• A window can have many layers. A sunspace, with its second layer of glass, will keep the cold away from the internal windows. Light can result in heat and, in very hot climates, dark interiors will keep rooms cooler. Shutters can be used externally to control solar gain in hot climates at different times of the day and year. Shutters can be used internally in cool and temperate climates to keep excessive sunlight out but some warmth in. Shutters can be wind-permeable but keep the sun out. Once the light has passed through the glass the heat it contains is trapped inside the room and will not escape back out through the glass. Heavy curtains can be used to keep light out in summer (but not heat for the same reason) and warmth inside in winter.

• Consider the problem of glare in rooms. In particular high glare levels will make it difficult to read computer screens and view the TV. Glare is also an indication of very high day lighting levels that may indicate that rooms will also overheat in summer.

• Capture the view. Careful consideration should enable the designer to make maximum advantage of the views on offer from the site. If there are particular features of interest ensure that they are captured in the centre of the window frame rather than the foreground in front of them or the sky above them (Lynes, 1992).

Krister Wiberg sitting at his kitchen table in Sweden. Light is a powerful design issue and very important in creating the 'spirit' of a place.

Make sure that the windows are placed in rooms to enable you to use the furniture you want in the house. If you have low chests of drawers to be placed against the outer wall make sure the window sill is above them.

If you want to get light deep into a room use high windows. Think about the psychological effect of a window or door in a room. What will a window do for the degree of privacy you require? Do you want everyone in the street to be able to see you in a particular room? Will a large patio door window turn a room into a corridor? • Think about light as a sculptural medium that changes every daylight hour of the year. You can create dynamic sculptures in shade and light to great effect on floors and forms within the house. Grade light through the house with darker and lighter areas to create visual interest.

All the techniques above provide ways in which we can understand, and design for, the invisible workings of a building. There are, however, also issues that cannot be calculated, that are very important in creating that other invisible factor: the spirit of a place, and these are dealt with, by Christopher Day, in the following chapter.

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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