If you need to bring more light into your home without losing valuable wall-space, Clerestory windows could be the answer to your prayers. Although mainly seen in the commercial sector or in contemporary/smart houses and apartments, these little gems are windows at high level (above your eye line). They are often used by architects and designers producing individual homes for self-builders but despite this, many aspiring self-builders do not actually know what they are.
The term ‘Clerestory’ was originally applied to the wall containing the windows above the nave (that’s the middle bit often incorrectly called the Aisle) – so believe it or not, the Bride and Groom do not actually come down the aisle, they come down the nave! The windows created light and airiness in our magnificent cathedrals, which is exactly what the architects were trying to achieve; and as the building technology developed to create bigger and bigger openings in the structure, the amount of opaque glass got larger and more impressive.
The main aim was to impress and show off to other cities just how technologically advanced they were, but there is no doubt we are still impressed, even today, by so called curtain glazing or perhaps a well-placed little window that just manages by its position and orientation to allow some light to infiltrate into the otherwise darkest vestige of a house.
As house designers, it is this type of clerestory window that we are interested in because that little chink of light can be so effective in contemporary interior design. It can be unexpected, it can cast shadows picking up the sculptural nature of the structure and it can carry inside the mood of the day thus connecting you with the early morning sun, the turbulent sky or the hues of the setting sun.
From a practical standpoint, clerestory lighting can be useful to avoid overlooking in compact cities and it is the height of a window that determines how far light will penetrate into an otherwise gloomy room. Even with ordinary eye level windows, the width of the window will determine the light intensity in the room near the window; but if you want the light to penetrate then it is the height of the window that is important. There is also something to be said for orientating the clerestory window northwards because north light is more consistent and does not cause glare one minute requiring the blinds to be drawn and dinginess the next, making it necessary to turn the light on.
The other advantage in using north light is that solar gain and over-heating will not be a problem. Beware of using too much glass inclined to the south facing sky because of overheating, as you will not need such a big glass area anyway because the light, they will allow in is much more effective than the equivalent window area. Lastly you may wish to avoid roof lights in bedrooms unless you are a very sound sleeper as hail hitting glass is very noisy and can be quite scary.
Another useful feature of a clerestory window is when your self-build or new extension is often overlooked on one side by an ugly wall or other feature belonging to the adjoining house that is very close to you. Therefore, it will provide light at a high level but the narrow size of the window will mean that the ugly feature can hardly be seen.
Clerestory windows are also useful on single storey houses when there is a projection outside the building in the form of a corridor; which is used to get from the front to the rear of a long, thin single storey house. A clerestory window therefore, can help counter the effect of the corridor by reducing the amount of light that enters the house.
When it comes to first floors on houses, you will often find a clerestory window tucked under the roof at the head of a staircase, as many architects feel that staircases often end up depending on artificial light and therefore, if they are properly lit, they can become much more of a feature. Additionally; many architects like to tuck an upstairs clerestory window under the eaves; as you have no external wall structure above that has to be supported by the window frame.
High level windows if fitted with the means to open can be a real joy to allow stale air out of a living space as drafts can be avoided and, as heat rises, a natural flow of air will circulate upwards, pulling cool and fresh air in from outside, that’s if the space is designed with this in mind of course.
If you would like more information on how clerestory windows could work in your current home or proposed self-build home, please do contact Building Tectonics as we will be only too pleased to advise you.