Last year there were a number of UK house fires caused by downlights being covered with insulation and/or other debris. However, there are solutions to the problem of downlight fires and energy efficiency losses caused by downlights located in ceilings below lofts, as Rupert Coggon reports:
The Electrical Safety Council (ESC) has commissioned a study of various downlights with the BSI laboratories. As a result, the ECS concluded that for downlights to be used safely when penetrating an insulated loft space, the downlight (or protecting downlight cover) should meet the test requirements of BS EN 60598 – generally indicated by use of the capped-F symbol (Figure 1 bottom left).
This test standard is very difficult to pass and there are very few products that meet the full requirements. The standard ensures that, even if the downlight is fully buried in insulation, it will not overheat the lamp, or the surrounding insulation.
Furthermore, the downlight or protecting downlight cover should be tested and approved for use with the increasingly common dichroic lamps. These recommendations are featured in the summer 2010 edition of the ESC’s ‘SwitchedOn’ magazine.
Most reputable downlight manufacturers believe that every downlight cover should also be fully fire rated and so prevent the spread of fire into a loft space, as well as ensuring that the downlights themselves do not become the source of a fire. One modern range of downlight loft covers not only fully meets the ESC’s recommendations but also offer a full fire rating as well, this gives 100% peace of mind to the householder. This range of downlight loft covers (Figure 2 below) have been tested to the most onerous levels of the capped-F standard with both aluminium and dichroic lamps types up to and including 50W.
Energy efficiency and downlight airtightness
Many building are now subject to mandatory airtightness and insulation continuity testing and inspection. However, the use of recessed downlights has long been recognised as a major source of energy loss and they are major culprits in buildings failing to meet the airtightness criteria. Indeed, the use of many downlights can easily reduce the efficiency of loft insulation by 50%, or even more. Recessed downlights, therefore, need suitable protection to ensure compliance.
A typical recessed downlight can allow 20m3 of air to pass at the standard test pressures – this represents a huge energy loss and almost a guarantee of airtightness test failure. The fitting of suitable downlight loft covers stops the flow of air at normal building pressure differentials, so preventing the loss of heat energy. Figure 3 above shows an air-tightness comparison of a downlight fitted with a loft cover against a downlight without such a cover.
Insulation continuity
If a downlight has the insulation removed from around it, a great deal of energy is lost via cold bridging, both through the downlight and through the un-insulated area of the ceiling. This also dramatically reduces the overall efficiency of the insulation.
The fitting of a suitable state-of-the-art downlight loft cover allows the insulation to be run directly over the downlight and cover, so that the insulation layer remains continuous and all the energy is retained in the room.
In fact, when such loft covers are fitted, the energy efficiency of a downlit ceiling is very close to that of a ceiling with surface mounted lighting, as the negative effects of fitting the downlights are essentially eradicated. The cartoon, (Figure 4 below) illustrates the principle!
For both new build, and as a low cost, easy and efficient method of improving the thermal performance of an existing ceiling, the fitting of such loft covers is an ideal solution, in addition to making the downlights 100% safe, plus meeting and surpassing all current recommendations and fire legislation.
