search.noResults

search.searching

note.createNoteMessage

search.noResults

search.searching

orderForm.title

orderForm.productCode
orderForm.description
orderForm.quantity
orderForm.itemPrice
orderForm.price
orderForm.totalPrice
orderForm.deliveryDetails.billingAddress
orderForm.deliveryDetails.deliveryAddress
orderForm.noItems
FINANCE & INSURANCE 51


TACKLING THE IMPACT OF THERMAL BRIDGING


With the drive towards improved energy efficiency, thermal bridging has become a ‘hot topic’ for housebuilders. Insulation manufacturer Marmox explains why, and describes some solutions to the problem.


t has been calculated by The Energy Saving Trust that in a typical detached property, an unaddressed thermal bridge can account for 30 per cent of a building’s heat loss.


I


One of the worst areas of heat loss through a thermal bridge is where the floor meets the wall, allowing heat to be trans- mitted to the outside. In this area, up to 50 per cent of heat in an otherwise well- insulated room can be lost.


The BRE defines a thermal bridge as follows: ‘A thermal bridge, also called a cold bridge, is an area of a building construction which has a significantly higher heat transfer than the surrounding materials. This is typically where there is either a break in the insulation, less insulation, or the insulation is penetrated by an element with a higher thermal conductivity. Where the building is situated in a cold climate (such as the UK) this can result in additional heat loss at these points.’


All Building Regulations in the UK and Ireland now say: “The building fabric


should be continuous over the whole building envelope and constructed so that there are no reasonably avoidable thermal bridges in the insulation layers caused by gaps in the various elements.”


BUILDING REGULATIONS


The non-dwelling and dwelling versions of the Building Regulations and Energy Conservation Part L (England, Wales, R.o.l), Section 6, Part D (Northern Ireland) require continuity of insulation at the wall-floor junction. Building regula- tions now require that heat loss due to thermal bridging should be taken into account in SAP calculations (for dwellings) and SBEM calculations (for buildings other than dwellings) at the design stage.


The heat loss through the wall/floor


junction is expressed as a ψ value, which is the linear thermal transmittance, and the cumulative heat loss as a Y-value. The design of the junctions should be based on Accredited Construction Details (ACDs) or Enhanced Construction Details (ECDs).


SAP, SBEM or other approved software then allocate a specific default Y-value for each type of junction.


STOPPING HEAT LOSS AT THE THERMAL BRIDGE


One of the latest solutions to addressing and stopping heat loss at the wall-floor junction is the use of high insulating, load-bearing building blocks, designed to replace the course of brick or block at the bottom of a wall.


The heat loss for a thermal bridge is determined by its linear thermal transmittance. This is measured in Watts for every metre of the thermal bridge – for every degree difference in the temperature between the inside and the outside of a room. The UK maximum allowable heat loss at a thermal bridge (wall/floor junction) is 0.16 W/m.K. Using Accredited Construction Details (ACD) can reduce this figure to 0.08 W/m.K. An Enhanced Construction Design (ECD) with additional interleaf insulation and edge insulation will be 0.04 W/m.K.


WWW.HBDONLINE.CO.UK


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60