Can electric cables be channelled into Recticel insulation boards?
No, as this would reduce the performance of the boards. Cables can penetrate the insulation with no detriment to the cable sheathing. Any cables penetrating or lying against insulation should be oversized to cater for increased operating temperature. If in doubt, consult a qualified electrician.
Can I install downlighters in conjunction with Recticel Insulation boards?
The temperature of a lamp can reach 2000C. Without adequate ventilation to allow the escape of heat, downlighters can cause fires. Recticel recommends the following measures are taken when installing downlighters: Downlighters should not be recessed into insulated ceilings if they penetrate the vapour control layer (VCL). This will result in them drawing warm moist air into the roof space where it could condense and drip back out of the fitting, causing a potential fire risk. Where downlighters are to be used they should be fitted into a false ceiling below the structural ceiling. Overheating can occur where thermal insulation is laid over existing downlighters and any associated transformers that are not designed to operate under these conditions. Cables and other electrical equipment should not be covered by insulation. In all cases, the downlighter manufacturer's instructions should be followed. They should specify the amount of space to be left around the back of the fitting, its fire rating, whether it can be covered with insulation, and the type/wattage of suitable lamps. If in doubt, consult a qualified electrician.
Can I use Recticel insulation products in a U-value calculation?
Yes. Recticel Insulation manufactures high-performance PIR insulation products for a range of wall, roof and floor applications.
The appropriate insulation product and thickness will depend on the construction build-up, required thermal performance and project requirements.
Use the U-value calculator to explore suitable construction and insulation specifications, or contact Recticel Insulation Technical Services for project-specific advice.
How do you calculate a U-value?
A U-value is calculated from the total thermal resistance of a building element, taking into account the different materials and layers within the construction build-up.
The basic principle is:
U-value = 1 ÷ total thermal resistance
Recticel Insulation's online U-value calculator can be used to assess the indicative thermal performance of different construction build-ups without having to calculate each layer manually.
How does insulation contribute to energy efficiency
Insulation reduces the transfer of heat through a building's walls, roofs and floors. This can help buildings retain heat during colder periods and limit heat gains during warmer periods.
High-performance insulation can therefore help reduce the energy required to maintain comfortable indoor temperatures over the lifetime of a building.
What does W/m²K mean?
W/m²K stands for watts per square metre Kelvin.
It is the unit used to express U-value and describes the rate of heat transfer through one square metre of a building element for a given temperature difference.
The lower the W/m²K value, the better the thermal performance.
What is a U-value?
A U-value measures how easily heat passes through a building element, such as a wall, roof or floor. It is expressed in watts per square metre Kelvin (W/m²K).
The lower the U-value, the better the thermal performance of the building element, as less heat is transferred through it.
What is the difference between a U-value and an R-value?
U-values take into account all elements of a construction, including thermal bridges. They can only be worked out by calculation. The R-value, or thermal resistance, is a measure of the insulation board on its own, dividing the thickness (in metres) by the thermal conductivity (lambda value, W/m.K). The R-value can be used to compare how different thicknesses of products with different lambda values perform comparatively.
What U-value do I need for a wall?
The required U-value for a wall depends on factors including the building type, construction method, project requirements and applicable Building Regulations.
Different wall constructions can achieve the same target U-value using different materials and insulation thicknesses.
Use the Recticel U-value calculator to assess different wall build-ups and insulation specifications.
Why is U-value important?
U-values are important because they help assess the thermal performance of a building's fabric.
A lower U-value means less heat is transferred through the building element, which can contribute to improved energy efficiency and help projects meet their thermal performance requirements.