Velux Product Manager, Grant Sneddon, discusses the daylight factor in building design and how to choose a window layout that maximises light.
Daylight has been an important feature of building development and design for many years. The placement of windows is key when trying to achieve optimum daylight, and it’s becoming increasingly important for builders to consider its role in every project.
It is clear that there is an opportunity for builders to make much better use of daylight during the design process.
Natural light ultimately benefits inhabitants’ health and well-being, and builders and installers can boost their businesses by demonstrating their knowledge of daylight and energy efficiency in home and building design.
Currently, there is no legislation which requires levels of natural lighting to be provided in dwellings, apart from a British Standard recommendation (BS8206-2:2008 Lighting for Buildings – Code of Practice for Daylighting).
As a guideline, building regulations recommend that if the area of glazing is much less than 20 per cent of the total floor area, then some parts of the dwelling may experience poor levels of daylight, resulting in the increased use of electric lighting. British Standards, therefore, advises building with as much access to natural lighting as possible.
Roof windows can typically let in up to twice as much light as a conventional vertical window because the glazing is pointed directly at the light source. They can bring more daylight into the heart of the building, illuminating hard to reach areas which may otherwise be quite dark.
By increasing glazed areas to allow for more daylight, there is also an increase in solar gain, which helps heat up the inside space during the colder months. This will go a long way towards reducing the energy needed for space heating and, in turn, can also reduce energy bills.
As a result of the effectiveness of roof windows, it may be tempting to not use the building regulation guide of 20 per cent glazing to floor area ratio. But why overlook the opportunity to enhance the internal space and maximise daylight in the design?
With added glazing comes a wealth of advantages for your customers as they are given the option to invest in a more desirable, energy efficient building. By promoting the long-term benefits of additional windows, which include added property value, a healthier indoor climate and a more aesthetically pleasing design, your customers will be confident that every building decision you make has their best interests in mind.
It’s important when looking at the structure of a building that it has as much access to natural daylight as possible. You should think about how and where daylight enters, not only factoring in the amount of windows but also the placement and orientation of them.
The height from the floor to ceiling and the length of the roof window should be considered in order to maximise light levels in the room. The developer must consider how the window will be operated, how much of the outside should be in view (ground, trees, sky etc.) and take into account the pitch of the roof. The lower the pitch, the longer the roof window should be to maximise the view out.
Choosing the Right Roof Windows
The most recognised type of roof window for homeowners and commercial builds is the centre-pivot roof window, but it’s also worth considering top-hung versions.
Top-hung roof windows open outwards with a handle at the bottom of the window, making them ideal for installations where the bottom of the window is easily within arm’s reach. Velux top-hung roof windows open 45° outwards for an unrestricted view and maximise the amount of natural daylight that can be allowed in.
Classic centre-pivot roof windows are ideal for lower installations and feature a top control bar, allowing the user to install the window lower than an equivalent top-hung operated roof window. This makes space for living areas with furniture beneath the roof window and helps create a perfect view of the outside surroundings whilst standing and when seated.
Using only the best high quality moulded polyurethane with an insulated timber core, the moisture resistant materials are well suited for humid rooms such as kitchens or bathrooms. A lacquered finish seals the windows ensuring their longevity.
The other interior finish option is natural pine, which has a protective triple-coat lacquer that helps to preserve the timber of the window. The natural pine finish is ideal for a warmer and more traditional look in living rooms and bedrooms.