The specifiers guide to rooflights

The specifiers guide to rooflights

Paul Trace from Lumen Rooflight offers some practical guidance to help specifiers choose the right product for their project.

Choosing the right rooflight for your project
Specifying the most suitable rooflight for your project can be anything but straightforward. Choosing the right product may well be determined by factors such as the type of building or roof in which it is to be installed, the effectiveness of light transmission, thermal insulation performance, or it may simply be a matter of aesthetics.

On any project the first thing to consider is the type of materials that are available. Steel is the obvious choice for period properties and barn conversions, but they are now also being more frequently specified in sleek new contemporary houses. Timber is a long-time favourite on homes of any style, but longer term maintenance may well rule this option out. PVCu is also an option, but it will not provide the slim frames that metal is capable of, nor the natural look of wood.

The important thing is to select a rooflight that matches the look and feel that you are trying to achieve with your project, be that a modern contemporary style or a more traditional design. The rooflight needs to blend in with the roof and the materials used throughout the build.

Rooflight specification will also be heavily influenced by the roof structure of the building into which the rooflight will be installed. Commercial, industrial and residential properties can vary greatly in this respect and there is a huge range of products designed specifically for flat and pitched roof structures.

Conservation style rooflights
If your project involves a listed property or one within a conservation area, you may be restricted in the type of rooflight you can install and the chances are that you will need a traditional or conservation style rooflight that complies with building regulations.

Modern conservation style rooflights should be as close to their original design as possible, and should compliment the property in which they are installed, with a minimal amount of framework visible.

Whilst there are many so called ‘conservation rooflights’ available, there only a handful that can comfortably pass this requirement. You should consider aspects such as the internal aesthetics, the functionality of the skylight and its components.

Thermal performance
Independent research conclusively proves that rooflights can save energy in many applications, and the greater the rooflight area the greater the potential savings. The amount of energy needed to light a building artificially is often much greater than the amount of energy used to heat it, and is often the greatest single energy use in operating the building.

Rooflights can have a major impact on the overall energy consumption of a building, cutting energy costs by reducing need for use of the electric lights. However, there are some products that perform well above the minimum recommended environmental standards that could bring about even greater benefits in terms of thermal performance.

Whatever your choice of material it is important that you check the energy rating performance and U Values of the glazing. It is worth asking exactly how each product performed under test conditions as there are many variables within the test that will differentiate between an average performing rooflight and an excellent one.

Lighting a building
Legislation issued in 2002 made it a legal requirement for buildings to have adequate natural daylight as part of the design. The legislation now states that a minimum 20 percent of the wall area or 10 percent of the roof area must comprise of light transmitting elements.

Due to the positioning of rooflights (ie on the roof!) they can provide a far superior light source than that of windows alone. It is, however, important to specify rooflights that maximize the glazing area and keep the framework to a minimum. It may seem fairly insignificant, but there are often huge variants from one product to the next, and it does make a considerable difference to the light coming into a building.

Glazing options
Once you have chosen the most appropriate material for your rooflight, you then need to consider the glazing options. Aside from thermal performance you need to decide if you need toughened glass, for additional safety and protection against falling objects. Toughened glass does not mean that it is suitable to walk on, so if you need to stand on a rooflight it will require specialist glazing.

Self cleaning glass is another option. This technological breakthrough was introduced to the UK in 2002 by Pilkington, and is still considered by many to be an impossible dream! Self cleaning glass is effectively the same as conventional glass, but with a specially developed coating on the outside, that once exposed to daylight, reacts in two ways. Firstly, it breaks down any organic dirt deposits through a photocatalytic process, and secondly, when it rains, instead of forming droplets, the water spreads evenly over the surface and takes the dirt off with it. It is kinder to the environment than ordinary glass and it is the ideal choice for situations where cleaning will be costly or difficult.

Quality v’s Cost
As with most things in life you get what you pay for, and this is particularly true when comparing the rooflight market. Prices often reflect the quality of manufacturing and materials used to produce roof windows. The rooflight may be one of a huge number of things that you specify on a project, but it is also one of the most important finishing touches to a property.

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