Technical information for rooflight specifiers, installers and building occupiers
GUEST BLOG by John Godley, Technical Manager for Hambleside Danelaw. Before the HSE introduced the CDM Regulations, they had already done some preliminary work on roof fragility. A simple ‘drop’ test onto a roof assembly was proposed, and if the impactor was retained, then the roof was deemed to be non-fragile. This testing, defined in…
It’s now widely accepted that natural daylight not only provides the best environment for people to work in: it saves energy and reduces CO2 emissions by reducing the need for electric lighting. However, the major concern with saving energy is not that the artificial lights get switched on; it is that they do not get…
This graph shows how roof light areas will affect illumination levels. In this example for a single storey building located in London, between the hours of 6am and 6pm daily, with roof lights providing 50% light transmission. You can see that as the roof light area along the bottom of the graph increases, the length…
As a general rule of thumb, daylighting in all types of building should be designed to provide adequate light levels in the room and on the work plane so that daylight is the main/or only source of light (autonomous) during daytime. For domestic properties, whilst there is little guidance on specific illumination levels in design,…
GUEST BLOG: John Godley, Technical Manager at Hambleside Danelaw, discusses the important factors to consider for an effective daylighting plan. Rooflights can provide up to three times more light than vertical glazing, and can provide more even and useable distribution of natural light into a building, particularly in large structures where light is required deep…
CIBSE Guide A provides data which allows us to determine the appropriate design and rooflight area to provide recommended light levels for a given application.Typically, for general retail and manufacturing areas, 500 Lux is the recommended level. The graph above shows how rooflight areas will affect illumination levels. In this example for a single storey…
The growing popularity of ‘walk-on’ rooflights – very high specification glass structures designed to floor loadings and therefore unsuitable for most rooflighting applications – has led to confusion amongst specifiers who often refer to ‘walk-on’ specification, when in fact their requirement is simply for a non-fragile rooflight. In response to frequent occurrences of mis-specification, NARM,…
Rooflight manufacturers are right to publish and promote the U-values of their products and low U-values are indeed an important contributing factor to overall building energy efficiency. However, rooflight area is actually the more significant factor in achieving Part L compliance. Generally speaking the larger the roof light area, the greater the reduction in energy…
It’s never a good thing to generalise, but the answer it would appear, may be more “Yes” than “No” in the case of some key topics. NARM recently conducted a survey of member companies to identify misunderstandings, problem topics or weak spots in specifications that they have been asked to quote against. Our aim being…