INSULATION 49 WARM WORDS


Jonathan Ducker of Kingspan Insulation explores how warm roof construction combined with advanced insulation materials can help meet our ambitious energy targets without compromising internal space.


I


n the next few months, the fi nal text for the Future omes tandard F will hopefully be confi rmed. ith all new homes expected to be required to use low carbon heating typically either a heat pump or district heating, the performance of the building fabric will play an important role in both supporting compliance with the requirements and ensuring homes are affordable to run. For this reason, many developers are looing to maximise the thermal performance of the roof construction. For properties where the roof space will be used as a liveable space, it is good practice to fi t insulation between and above the rafters. Using insulation with a low thermal conductivity can be especially benefi cial in this application, helping to ensure there is suitable headroom in the space and simplifying detailing to ensure a compliant new roof.


FUTURE HOMES STANDARD – WHAT TO EXPECT?


he overnment consultation on the Future omes tandard proposed two different options for the otional welling specifi cation. his is applied to a theoretical building of the same dimensions as the proposed home within the energy modelling software to generate the performance targets for the building. s with the existing standards, developers are free to depart from this specifi cation provided they meet the performance targets, limiting values such as worst-case U-values and any other mandatory requirements such as using low carbon heating.


side from the switch to low carbon heating, one of the proposed options is largely unchanged from the existing requirements in pproved ocument  22  22. he other includes some enhanced features, limiting air loss to 4 m3


/m2 .h   a with ventilation


provided via a mechanical ventilation heat recovery system, and using wastewater heat recovery and . urprisingly, neither of the


specifi cations requires the building fabric to be upgraded beyond the values in  22. his is despite the U-values in the nglish otional welling


WARM ROOF CONSTRUCTION CAN HELP ACHIEVE U-VALUES AS LOW AS 0.09 W/M²K


lagging signifi cantly behind the current equivalents in cotland and ales in most areas. ith the switch to low carbon heating appliances, which perform most effi ciently at lower fl ow temperatures than conventional boilers, ensuring homes retain heat well will be vital to allow them to be heated affordably. t is therefore worth looing to upgrade roof U-values to the same level as used within the current otional uilding in cotland  . m2


K. WARM ROOF


hen looing to reach this U-value, the thermal conductivity lambda value of the insulation is especially important, as this can signifi cantly impact the depth of the roof construction. he lower the thermal conductivity of the insulation, the more effective it is at slowing heat loss. his can allow the U-value to be met


with a slimmer construction than might be possible with materials with higher thermal conductivities. igid phenolic insulation boards are well suited for applications where ambitious U-values are needed, as they tend to have the lowest thermal conductivity of any commonly used insulation board as low as . mK.


long with the choice of insulation, it is also important for developers to consider the build-up they want to use, especially for room-in-the-roof constructions. n the past, the typical approach has been to fi t insulation between the rafters with a further layer of insulated plasterboard below. owever, even when designing the construction to allow phenolic insulation to fi ll the gap between  mm rafters, this can still require a substantial thicness of insulated plasterboard beneath just to reach a U-value of . m2


K as in WWW.HBDONLINE.CO.UK


An additional layer of breather membrane can be fi tted between two layers of roofi ng board to further minimise draughts and air loss in ‘between and over’ installations


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  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68