Thermal Efficiency Standards in New Dwellings

CI/SfB | |

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| (M2) |

Uniclass L6815

Residential New Build

Thermal Efficiency Standards in New Dwellings A guide to Approved Document L1A 2013 (England)

April 2014

Contents

Topic Introduction

3

Complying with ADL1A using SAP 2012

6

One Fabric Elemental Receipe for all house types

7

Party wall thermal by-pass

8

Pitched roof solutions

10

External wall solutions

12

Flooring solutions

18

How Knauf Insulation can help

21

Glossary

22

Energy performance certificates

23

Ho

Introduction Main changes in Approved Document L1A 2013 The 2013 version of Approved Document L1A (conservation of fuel and power in new dwellings) came into effect (in England only) on 6th April 2014. CO2 emissions The headline change is a 6% reduction in the carbon dioxide emissions from the mix of new dwellings relative to Approved Document L1A 2010 and is a step closer to the Governments aim of building zero carbon homes by 2016. The measurement of both the thermal performance and CO2 emissions associated with the dwelling under consideration will be calculated using the 2012 version of the Standard Assessment Procedure (SAP 2012). Fabric energy efficiency A new addition to ADL1A is the introduction of a Target Fabric Energy Efficiency standard (TFEE). The TFEE accounts for a dwelling’s combined annual heating and cooling load measured in kWh/m2, for which a limit is set by SAP based on the performance of a notional dwelling of the same size and shape as that being assessed. The notional dwelling has fixed values for the fabric performance (U-values, thermal bridging, air leakage etc) as detailed in Appendix R of SAP 2012. A 15% increase is then added to the TFEE, giving the designer some additional design flexibility. When a new dwelling is built in line with the reference specification it will meet the carbon emissions and fabric energy efficiency requirements of ADL1A. High efficiency alternative systems Before construction of a new building starts, the person who is to carry out the work must analyse and take into account the technical, environmental and economic feasibility of using high-efficiency alternative systems (such as the following systems) in the construction, if available: (a) Decentralised energy supply systems based on energy from renewable sources (b) Cogeneration (Combined Heat and Power) (c) District or block heating or cooling, particularly where it is based entirely or partially on energy from renewable sources (d) Heat pumps There is no need to install any of the above measures as they may have been found to be impractical (due to size or location of site for instance) or that none of the measures was cost effective however, developers need to provide a report to show that they have been considered. Limiting U-values The limiting elemental fabric U-values remain as they were in ADL1A 2010. However, in practice a much more thermally efficient fabric will have to be specified in order to meet the Target Fabric Energy Efficiency (TFEE) rate – see page 7 for Knauf Insulation’s elemental fabric recipe.

Limiting fabric parameters - Part L1A -2013 Element Roof Wall Floor Partywall Swimming pool basin Windows, rooflights and doors Air permeability

2010 U-value (W/m2k) 0.20 0.30 0.25 0.20 0.25 2.00 3 10.00m /h/m2 @50pa

2013 U-value (W/m2k) 0.20 0.30 0.25 0.20 0.25 2.00 3 10.00m /h/m2 @50pa

Technical Support Team Tel: 01744 766666 www.knaufinsulation.co.uk

3

Main changes in SAP 2012 Regional variations • Wind speed – has an impact on ventilation, exposure and wind turbines • Allowance for height above sea level included in external temperature data • Solar radiation – effects solar gains and performance of renewable technologies Emission factors (CO2/kWhr) •S mall increase for electricity and a bigger increase for gas and oil

‘Fabric First’ – why exceed minimum requirements Part L of the Building Regulations sets minimum standards for the thermal performance of the building fabric elements (roof, wall, floor, windows and doors) by reference to limiting U-values. However, it should be remembered that this is the minimum level of performance required so why settle for this when a much more efficient insulated fabric can quite easily be achieved and delivers many long term associated benefits such as:

Fuel factors

•

reduced energy bills

• F uel price and primary energy factors have been revised

•

reduced CO2 emissions

•

reduced reliance on renewable technologies

Others

•

more comfortable internal environment with less temperature fluctuations

• Increase in number of thermal bridges to be considered • Increased options for heat loss from primary hot water pipes

Target Fabric Energy Efficiency (TFEE) A new addition to ADL1A is the introduction of a Target Fabric Energy Efficiency standard (TFEE). The TFEE accounts for a dwelling’s combined, annual heating and cooling load measured in kWh/m2, for which a limit is set by SAP based on the performance of a notional dwelling of the same size and shape as that being assessed. The notional dwelling has fixed values for the fabric performance (U-values, thermal bridging, air leakage etc.) as detailed in Appendix R of SAP 2012 a 15% increase is then added to the TFEE, giving the designer some additional design flexibility. When a new dwelling is built in line with the reference specification it will meet the carbon emissions and fabric energy efficiency requirements of ADL1A. However, compliance with the TFEE standard can easily be achieved by adopting fabric U-values other than those referred to in Appendix R.

Forward thinking developers could take the approach of amending their designs now and adopting a highly insulated fabric which would result in future requirements being met by renewable technologies being simply ‘bolted on’ to their existing designs. It is worth remembering that if the renewable technologies fail, are not adequately maintained or suffer from reduced performance over time a well insulated dwelling will still provide a highly efficient fabric which requires no maintenance in order to deliver its thermal performance – and it’s there for the lifetime of the dwelling. Revised guidance for minimising thermal bridging Four ways of showing compliance: 1. Adopt DCLG Approved Construction Details 2. Adopt details calculated by a person with suitable expertise and experience - BRE Report BR 497 3. Default values from Table K1 in SAP 2012 4. Use default `Y` value of 0.15W/m2K rather than individual psi values The quality assured construction details schemes proposed in ADL1A 2010 have been dropped

Thermal bridging The size of a thermal bridge is determined by its thermal transmittance value (psi value) whilst the ability of a thermal bridge to prevent surface condensation from forming is determined by its temperature factor (f-factor). The overall impact of thermal bridging on a dwelling is determined by the “Y-value” which is calculated by dividing the total area of the external elements of the dwelling by the sum of the length and psi value of each thermal bridge. There is a significant increase in the number of highly insulated dwellings due to the ever more stringent regulatory requirements for the reduction of heat loss and CO2 emissions from dwellings and this is something which will increase greatly as we move towards zero carbon new dwellings in 2016. One impact of highly insulated dwellings is the increased contribution to the overall heat loss from the dwelling due to the impact of thermal bridges (two or three dimensional) to the degree that it is now more vital than ever that good design detailing and on-site construction practises are employed to ensure that heat loss through the junctions of building elements and around openings is kept to a minimum. Along with the need to minimise heat loss through thermal bridges there is the secondary requirement to keep the surface temperature of the internal surface of the building fabric above a minimum level in order to prevent surface condensation and mould growth from occurring, thereby helping to maintain a healthy internal environment and also prevent deterioration of the building fabric. The thermal bridges detailed in the table below have been compiled by Knauf Insulation experts and all have an f-factor in excess of 0.75 which is sufficient to prevent surface condensation from forming in dwellings. The table below details the psi values applicable to each junction assigned to the house types on page 7.

Psi Values Ψ

2-D modelling

The specification of Knauf Insulation Psi values and construction details will have a positive influence on the thermal performance of the building by significantly reducing heat loss through junctions and openings, especially when compared to the most Psi values referenced in Appendices K and R of SAP 2012

The calculation of linear thermal transmittance (Ψ) and the temperature factor (f-factor) need to be based on the 2-D modelling techniques described in BRE Information Paper IP 1/06, Assessing the effects of thermal bridging at junctions and around openings in the external elements of buildings and BR 497, Conventions for calculating linear thermal transmittance and temperature factors.

The psi value tables below indicate which junction descriptor to select when creating SAP calculations. If specifying (and building) Knauf Insulation construction details and calculated Psi values the “whole house” Y-value can be considerably reduced thereby, assisting compliance with the carbon emission and Target Fabric Energy Efficiency requirements of Approved Document L1A.

Appendix K Psi values from SAP 2012

Junctions with an external wall

Junctions with a party wall c)

Reference values of Psi for junctions (England)

Approved Ψ

Default Ψ

Table R2 Ψ

The analysis of an eaves detail below assumes the following: Knauf Insulation calculated Psi values Ψ

Detail reference

Junction detail

(W/mK)

(W/mK)

(W/mK)

(W/mK)

E2

Other lintels (including other steel lintels)

0.30

1.00

0.05

0.02

E3

Sill

0.04

0.08

0.05

0.03

E4

Jamb

0.05

0.10

0.05

0.02

E5

Ground floor (normal)

0.16

0.32

0.16

0.34

E6

Intermediate floor within a dwelling

0.07

0.14

0.00

0.00

E10

Eaves (insulation at ceiling level)

0.06

0.12

0.06

0.06

E12

Gable (insulation at ceiling level)

0.24

0.48

0.06

0.05

E13

Gable (insulation at rafter level)

0.04

0.08

0.08

0.07

E16

Corner (normal)

0.09

0.18

0.09

0.06

E17

Corner (inverted - internal area greater than external area)

-0.09

0.12

-0.09

-0.10

E18

Party wall between dwellings c)

0.06

0.12

0.06

0.05

P2

Intermediate floor within a dwelling

N/A

0.00

0.00

0.00

P4

Roof (insulation at ceiling level)

N/A

0.24

0.12

0.04

P5

Roof (insulation at rafter level)

N/A

0.48

0.08

0.05

R1

Head

N/A

0.08

0.08

N/A

R2

Sill

N/A

0.06

0.06

N/A

R3

Jamb

N/A

0.08

0.08

N/A

R4

Ridge (vaulted ceiling)

N/A

0.08

0.08

N/A

R5

Ridge (inverted)

N/A

0.04

0.04

N/A

R6

Flat ceiling

N/A

0.06

0.06

N/A

R7

Flat ceiling (inverted)

N/A

0.04

0.04

N/A

R8

Roof wall (rafter)

N/A

0.06

0.06

N/A

R9

Roof wall (flat ceiling)

N/A

0.04

0.04

N/A

• 400mm Earthwool Loft Roll 44 • Aircrete block inner leaf (λ = 0.15 W/mK) • External cavity fully filled with 100mm Supafil 34 (λ = 0.034 W/m2K)

Junction detail

Temperature distribution

Junctions within a roof or with a room-in-roof

c) Value of Ψ is applied to each dwelling

Linear thermal transmittance y=

0.023 Temperature factor

f=


0.932

5

How to comply with ADL1A using SAP 2012 Whole-house specifications – one elemental recipe for all house types The following specifications show how, for a range of typical dwelling types, it is possible to meet the CO2 emission and Fabric Energy Efficiency requirements of Approved Document L1A 2013 using forms of construction with reasonably achievable U-values, without the need for mechanical ventilation or new low-energy technologies.

The specifications have been devised using the SAP 2012 methodology, using U-values appropriate to the use of Knauf Insulation products and making reasonable assumptions about other aspects of the design, e.g. air permeability rates and the type of space heating – see Tables below.

Five typical dwelling types have been analysed, some with mid and end-terrace variants. The U-values for each element of the dwelling are shown on the diagram opposite, together with cross references to the relevant elemental solutions tables.

Detached - 4 bedrooms

Mid terrace - 3 bedrooms

End terrace - 3 bedrooms

Dwelling type

2.5

2.5

2

2

2

Storeys

0.11

0.11

0.11

0.11

0.11

Roof U-value

0.25

0.25

0.25

0.25

0.25

Wall U-value

0.13

0.13

0.13

0.13

0.13

Floor U-value

0.20

0.20

n/a

n/a

n/a

Sloped roof U-value

Zero

Zero

Zero

Zero

Zero

Party wall U-value

0.20

0.20

n/a

n/a

n/a

Dormer roof U-value

0.30

0.30

n/a

n/a

n/a

Dormer wall U-value

1.30

1.30

1.30

1.30

1.30

Window U-value

1.20

1.20

1.20

1.20

1.20

Door U-value

89.50

89.50

89.50

89.50

89.50

Boiler efficiency (%)

5.00

5.00

5.00

5.00

5.00

Air permeability

0.065

0.044

0.024

0.054

0.037

Thermal bridging

165.59

160.67

177.61

190.16

184.97

Thermal mass

14.78

16.03

15.89

16.71

17.96

TER

14.60

15.97

15.63

16.68

17.91

DER

40.81

47.25

52.13

42.32

48.84

TFEE

36.33

42.59

45.69

37.24

43.75

DFEE

Pass

Pass

Pass

Pass

Pass

Pass/Fail

Other building element specification results

End terrace two and a half storey - 3 bedrooms

U-value specifications

Mid terrace two and a half storey - 3 bedrooms

Ventilation

Parameter 100%

Natural

Value

Standard parameters for all dwelling types

Low energy lighting

For project specific calculations contact our Technical Support Team on 01744 766666

One fabric “Elemental Recipe” for all house types

100mm Earthwool DriTherm Cavity Slab 34 Super or Supafil 34

75mm or 100mm Earthwool Masonry Party Wall Slab or Supafil Party Wall

Masonry party wall - fully filled Effective U-value of zero

Masonry cavity wall - fully filled Block - 0.15 W/mK U-value - 0.25 W/m2K 150mm or 200mm* Polyfoam ECO Floorboard Standard

140mm Earthwool FrameTherm 40

100mm and 300mm** Earthwool Loft Roll 44

Ground bearing concrete floor U-value - 0.13 W/m2K

Timber frame wall U-value - 0.25 W/m2K

Loft insulation U-value - 0.11 W/m2K

SAP 2012 - standard parameters for all dwelling types Element Roof - ceiling level Roof - rafter level External walls Ground floor Windows Doors

U-value (W/m2K) 0.11 0.20 0.25 0.13 1.30 1.20

Page No 11 11 13 18 – –

Parameter Party wall effective U-value Thermal bridging Air permeability (m3/hr per m2) Ventilation Low energy lighting Gas condensing boiler efficiency (%)

Value Zero 0.02 - 0.05 5.00 Natural 100% 89.50

*Dependent on P/A ratio **(2 x 150mm over joists)


7

Solutions to party wall bypass Research headed by Leeds Metropolitan University, MIMA (the Mineral Wool Insulation Manufacturers’ Trade Association) and Knauf Insulation has confirmed that an effective zero U-value can be achieved by fully filling the cavity of a masonry wall with glass mineral wool of a minimum 18kg/m3 density and placing a sleeved flexible cavity barrier at the junction of the party wall with external elements.

Junctions of party walls with external walls E-WM-22 masonry party wall with plasterboard on dabs

Additionally, if the cavity is fully filled, this may have implications for sound transmission and the ability to meet the requirements of Part E. With this in mind, developers can now adopt a Knauf Insulation Robust Detail as follows: •

E-WM-22 - built in solution with Earthwool Masonry Party Wall Slab

•

E-WM-28 - blown in solution with Supafil Party Wall

•

E-WT-2 - built in solution with Earthwool Timber Frame Party Wall Slab

Robust Detail t an Compli

External wall cavity fully filled with Supafil or Earthwool DriTherm Cavity Slabs Cavity barrier Party wall cavity fully filled with 100mm Earthwool Masonry Party Wall Slab Plasterboard on dabs (no parge coat)

Junctions of party walls with external walls E-WM-28 masonry party wall with plasterboard on dabs External wall cavity fully filled with Supafil or Earthwool DriTherm Cavity Slabs Cavity barrier Party wall cavity fully filled with Supafil Party Wall Plasterboard on dabs (no parge coat)

Junctions of party walls with external walls E-WT-2 timber frame party wall with sheathing board Earthwool FrameTherm in external walls Cavity barrier Party wall cavity fully filled with Earthwool Timber Frame Party Wall Slab Earthwool FrameTherm 40 2 or more layers of plasterboard Sheathing Board

Robust Detail t an Compli

Table 1 Robust Detail Separating Walls and Party Wall Bypass Solutions Robust Detail Wall Type

Minimum Cavity Width (mm)

Block Type

Block Density (kg/m3)

Wall Finish

Parge coat

CfSH Credits

Zero U-value Yes

Supafil Party Wall 3

Earthwool Masonry Party Wall Slab 3

E-WM-1

75

Dense

1850 to 2300

Wet plaster

Yes

0

E-WM-2

75

Light aggregate

1350 to 1600

Wet plaster

Yes

1

Yes

3

3

E-WM-3

75

Dense

1850 to 2300

Plasterboard on dabs

Yes

1

Yes

3

3

E-WM-4

75

Light aggregate

1350 to 1600


Yes

1

Yes

3

3

Yes

1

Yes

3

3

E-WM-5

75

Besblock

1528

Plasterboard on dabs on cement render

E-WM-6

75

Aircrete

600 to 800


Yes

1

Yes

3

3

E-WM-10

75

Aircrete - thin joint

600 to 800


Yes

0

Yes

3

3

E-WM-11

100

Light aggregate

1350 to 1600


Yes

3

Yes

3

3

E-WM-13

75

Aircrete - thin joint

600 to 800


Yes

3

Yes

3

3

E-WM-16

100

Dense

1850 to 2300


Yes

3

Yes

3

3

E-WM-18

100

Dense

1850 to 2300

Wet plaster

Yes

3

Yes

3

3

E-WM-19

100

Dense or light aggregate

1350 to 1600 or 1850 to 2300


Yes

4

Yes

3

3

E-WM-21

100

Light aggregate

1350 to 1600

Wet plaster

Yes

3

Yes

3

3

E-WM-22

100

Light aggregate

1350 to 1600


No

3

Yes

–

3

E-WM-25

100

Porotherm

n/a


Yes

3

Yes

–

3

– 3

3

E-WM-26

100

Besblock

1528


No

1

Yes

E-WM-28

100

Light aggregate

1350 to 1600


No

3

Yes

–

Timber Frame Robust Detail Wall Type

Minimum Cavity Width (mm)

Sheathing

Wall Finish

External (flanking) wall

CfSH Credits

Zero U-value

Eathwool Timber Frame Party Wall Slab

E-WT-2

50

9mm(min) thick board

2 or more layers of gypsum-based board

Outer leaf masonry-min 50mm cavity

1

Yes

3

The party wall bypass mechanism This is a process whereby heat is lost to an open party wall cavity containing cold air which has entered from the external flanking building elements, mainly external walls. In fact, heat is lost from both sides of the party wall to the external environment, the extent being affected by external climatic conditions and stack effect within the party wall cavity. It is important to be aware that, where heated spaces extend into the loft, there is also a potential thermal by-pass where the party wall meets the roof covering. Although the thermal bypass is expressed as a U-value, it is not a U-value in the normal sense because the heat loss mechanism is a combination of heat loss effects, e.g. through the party walls, by air circulation from the party wall cavity to other building cavities and, finally, to the external environment.

The importance of zero U-values and complying with ADL1A ADL1A states that, in the absence of specific independent scientific field evidence, it is reasonable to apply indicative U-values (see Table 2 ), provided that any edge sealing is aligned with the thermal insulation in adjacent external elements. Within ADL1A the notional building, which is used to calculate the Target Emission Rate (TER), includes a party wall heat loss

of zero. Clearly, using a construction option with an effective U-value of more than zero will result in an increase in the Dwelling Emission Rate (DER) making it more difficult to achieve the ADL1A carbon emissions standards. The difference between adopting a zero effective U-value for the party wall and leaving the cavity unfilled, and with no effective edge sealing can result in an increase in the Dwelling Emission Rate (DER) of up to 15% for a typical end terrace house. So clearly, there is a significant advantage in adopting a zero U-value solution, this will become even more important as we approach 2016 and the requirement to build zero carbon homes.

Table 2 U-values for party walls Wall construction

U-value (W/m2K)

Solid

0.00

Unfilled cavity with no effective edge sealing

0.50

Unfilled cavity with effective edge sealing around all edges and in line with insulation layers in abutting elements

0.20

Fully filled cavity with effective edge sealing around all edges and in line with insulation layers in abutting elements

0.00


9

Pitched roof solutions The impact of heat loss through roofs The roof comprises a large percentage of the external shell of most dwellings and is a key interface between the internal and external environment. Usually, the most exposed surface of the building, the roof, must not only be weather-tight and waterproof, but also must be well insulated to minimise heat loss. Without loft insulation, as much as 25% of a house’s heating costs could be attributed to heat lost through the roof. Loft insulation acts as a blanket, trapping heat rising from below. It is a simple and effective way to reduce heating bills. Installing Earthwool Loft Rolls delivers thermal, acoustic and fire resistance benefits to any roof, as well as being the most cost-effective solution for insulating a pitched roof at ceiling level.

Pitched roof solutions The following pages include solutions for roofs insulated both at ceiling level and at rafter level. Whilst both types of roof are required to provide high standards of thermal insulation, roofs at rafter level should also be designed to provide protection from noise. In this case noise from road traffic and airplanes, rainfall drumming on the roof and flanking sounds from attached properties could cause considerable nuisance within the rooms created in the roof void.

BBA U-value Competency Scheme All U-values referred to in this publication have been compiled in accordance with the BBA/TIMSA U-value Competency Scheme.


Table 3 Ceiling level – between and above joists

Between joists

Over joists

Typical U-values (W/m2K)

100

450 (3x150)

0.08

• Products have an A+ generic Green Guide rating

100

400 (2x200)

0.09

• Zero ODP and GWP rated products

100

340 (2x170)

0.10

100

300 (2x150)

0.11

• Products are compression packed to reduce transport related CO2 emissions

100

200

0.14

100

170

0.16

100

400 (2x200)

0.08

100

300 (2x150)

0.10

100

200

0.13

100

150

0.16

Insulation thickness (mm) Insulation over ceiling

Earthwool Loft Roll 44 U-value 0.08—0.16

Earthwool Loft Roll 40

• Non-combustible products with the highest Euroclass A1 rating

• Product manufacture has a very low environmental impact • Glass mineral wool insulation products provide the lowest cost solution for insulating a roof • Suitable for use with traditional and vapour permeable roofing membranes

Joist sizes assumed to be 100x48mm at 600mm centres (8% bridging plus 1% for cross noggings).

Table 4 Rafter level – between and below rafters • Achieves low U-values even with shallow rafters

Knauf PIR Laminate* thickness below rafters (mm) Rafter Depth (mm)

Insulation thickness between rafters (mm)

25

40

55


Earthwool Rafter Roll U-value 0.13—0.23

225

200

0.16

0.14

0.13

200

175

0.17

0.15

0.14

175

140

0.19

0.17

0.15

150

125

0.20

0.18

0.16

• Earthwool Rafter Roll is compressible so it is easy to friction fit tightly between rafters and avoid cold air penetration • Significantly improves the acoustic performance of the roof • Can be used along with an extra layer of plasterboard to satisfy the requirements of Robust Details to resist flanking sound around separating walls • Longer rolls with greater coverage per roll than equivalent products

Rafter depth equals Earthwool Rafter Roll thickness plus 25mm unventilated airspace. Rafters are 38mm at 600mm centres (bridge of 6.33%). Plasterboard facing on Knauf PIR Laminate is 9.50mm (λ = 0.210). *Available from Knauf Drywall.

Table 5 Dwarf walls in pitched roofs • Achieves low U-values even with shallow rafters

Knauf PIR Laminate* thickness on face of timber studs (mm) 25

40

55

140

0.18

0.16

0.14

125

0.20

0.17

0.15

100

0.22

0.19

0.17

Earthwool Rafter Roll

Plasterboard facing on Polyfoam Linerboard is 9.50mm (λ = 0.210). Plasterboard facing on Knauf PIR Laminate is 9.50mm (λ = 0.210). Timber stud depth equals insulation thickness (bridge of 7.83%). Additional airspace resistance of 0.50 m2K/W. *Available from Knauf Drywall.


• Earthwool Rafter Roll is compressible so it is easy to friction fit tightly between rafters and avoid cold air penetration • Significantly improves the acoustic performance of the roof • Can be used along with an extra layer of plasterboard to satisfy the requirements of Robust Details to resist flanking sound around separating walls • Longer rolls with greater coverage per roll than equivalent products

11

External wall solutions The impact of heat loss through external walls The greatest proportion of heat loss from a typical house, as much as 35%, is through the walls, mainly because of their large area. Installing thermal insulation slows down the rate of heat loss, thereby giving immediate savings on fuel bills. Providing an efficient building envelope is vitally important in meeting the requirements of ADL1A of the Building Regulations and achieving the higher Code levels of the Code for Sustainable Homes.

Innovation driving change Partial cavity fill and insulated dry linings, for example, are likely to become less popular as thermal insulation values rise, with full fill masonry cavity walls and highly insulated timber framed walls being able to achieve improved U-values using slightly wider cavities and deeper timber studs. There is likely to be greater innovation in other forms of construction, especially where rainscreen cladding is used to protect the insulation layer. The recent tightening of thermal regulations has placed a greater emphasis on avoiding thermal bridging and ensuring an airtight external envelope. As a result, detailing at junctions is likely to become more complex and sophisticated. On the following pages we explore a number of innovative constructions which maximise thermal and, where appropriate, acoustic performance.



Table 6 Masonry cavity walls – full fill with built-in glass mineral wool Brick outer leaf/cavity/100mm block inner leaf and plasterboard on dabs

Insulation thickness (mm)

Lightweight aircrete (λ=0.11)

Standard aircrete (λ=0.15)

High strength aircrete (λ=0.19)

Lightweight aggregate (λ=0.28)

Medium density (λ=0.45)


• Non-combustible products with the highest Euroclass A1 rating • Earthwool DriTherm Cavity Slabs are the lowest cost, built-in solution, for masonry cavity walls

Earthwool DriTherm 32 Ultimate U-value 0.15—0.329

• Earthwool DriTherm Cavity Slabs have an A+ generic Green Guide rating

200 (100+100)

0.13

0.14

0.14

0.14

0.14

175 (100+75)

0.15

0.15

0.16

0.16

0.16

150 (75+75)

0.17

0.17

0.18

0.18

0.19

125

0.20

0.20

0.21

0.21

0.22

100

0.23

0.24

0.25

0.25

0.26

Earthwool DriTherm 34 Super 200 (100+100)

0.14

0.14

0.15

0.15

0.15

175 (100+75)

0.16

0.16

0.16

0.17

0.17

150 (100+50)

0.18

0.18

0.19

0.19

0.20

125

0.20

0.21

0.22

0.22

0.23

100

0.24

0.25

0.26

0.27

0.27

Earthwool DriTherm 37 Standard 200 (100+100)

0.15

0.15

0.16

0.16

0.16

175 (100+75)

0.17

0.18

0.18

0.17

0.19

150 (100+50)

0.17

0.17

0.18

0.18

0.19

125

0.22

0.23

0.23

0.24

0.25

100

0.26

0.27

0.27

0.28

0.29

• No requirement for fire stops as all Earthwool DriTherm products are completely non-combustible and fully fill the cavity • No requirement for acoustic cavity stops at junctions with separating floors and walls • Products are robust and resilient making them easy to handle, store on site and install • Formally guaranteed for 50 years to resist the transmission of liquid water and retain their thermal performance • 35 year proven performance • All products have British Board of Agrément Certification for all exposure zones

Block sizes are assumed to be 440 x 215mm, with 10mm mortar joints. Wall ties are assumed to be stainless steel with a cross-sectional area of no more than 12.5mm2 for structural cavities up to 150mm wide and two part wall ties with a cross-sectional area of 25mm2 for larger cavities. U-values are based on an internal finish of 12.5mm plasterboard (λ =0.210 W/mK) on dabs.


13

External wall solutions (continued)

Table 7 Masonry cavity wall – full fill with injected glass wool • Supafil products have an A+ generic Green Guide rating

Brick outer leaf/cavity/100mm block inner leaf and plasterboard on dabs


Lightweight aircrete (λ=0.11)

Standard aircrete (λ=0.15)

High strength aircrete (λ=0.19)

Lightweight aggregate (λ=0.28)

Medium density (λ=0.45)


• Suitable for any cavity width • No waste on site

Supafil 34 U-value 0.16—0.31


• Installed by approved contractor

200

0.14

0.14

0.15

0.15

0.15

175

0.16

0.16

0.16

0.17

0.17

150

0.18

0.18

0.19

0.19

0.20

125

0.20

0.21

0.22

0.22

0.23

100

0.24

0.25

0.26

0.27

0.27

200

0.16

0.17

0.17

0.17

0.18

175

0.18

0.18

0.19

0.19

0.20

150

0.20

0.21

0.21

0.22

0.22

125

0.23

0.24

0.25

0.25

0.26

100

0.27

0.28

0.29

0.30

0.31

Supafil 40

• British Board of Agrément Certification for all exposure zones • Product guaranteed to resist moisture penetration • Wall construction quicker than with built-in cavity wall insulation • Installed after wall constructed when building is watertight

Block sizes are assumed to be 440 x 215mm, with 10mm mortar joints. Wall ties are assumed to be stainless steel with a cross-sectional area of no more than 12.5mm2 for structural cavities up to 150mm wide and two part wall ties with a cross-sectional area of 25mm2 for larger cavities. U-values are based on an internal finish of 12.5mm plasterboard (λ = 0.210 W/mK) on dabs.



Table 8 Timber frame wall – single layer insulation between studs Masonry outer leaf


Insuation thickness of 140mm

With standard breather membrane U-value 0.22—0.32

With Low-E breather membrane

Tile/timber clad outer leaf

Earthwool FrameTherm 32

0.26

0.29


0.27

0.29


0.29

0.31


0.31

0.32


0.22

0.27


0.23

0.28


0.24

0.29


0.25

0.30

• Non-combustible products with the highest Euroclass A1 rating • Earthwool FrameTherm products have an A+ generic Green Guide rating • Products are compression packed to reduce transport related CO2 emissions • Lightweight and easier to cut and handle than rigid foam boards • Much faster to install than rigid boards, which require very accurate cutting • Products are compressible, and friction fit between timber studs avoiding cold bridging at joints • Improves the acoustic performance of the wall

Table 9 Timber frame wall – single layer insulation between studs with a low e service void Masonry outer leaf with Low-E breather membrane



140

0.19

0.21

0.23

90

0.24

0.28

0.30


140

0.20

0.22

0.24

90

0.25

0.29

0.32


140

0.20

0.23

0.25

90

0.26

0.30

0.33


140

0.21

0.24

0.25

90

0.26

0.31

0.33


• All the advantages of using Frametherm in the application above apply • Provides a service void helping to preserve the integrity of the vapour control layer


Insuation thickness (mm)

U-value 0.19—0.33

Masonry outer leaf with standard breather membrane

• Improves the thermal performance of timber frame walls within a standard stud width • Achieves low U-values in a 90mm stud

15


Table 10 Timber frame – single layer blowing wool system

Supafil Frame and standard breather membrane

U-value 0.18—0.39

Supafil Frame and Low-E breather membrane



Masonry outer leaf

200

0.21

0.22

• Supafil Frame has an A+ generic Green Guide rating

140

0.27

0.29

• No waste on site

90

0.38

0.42

• Completely fills all gaps, voids and hard to reach areas around services

200

0.18

0.21

140

0.23

0.28

• Installation is quick and clean, without adhesives or added moisture

90

0.31

0.39

• Blown from the inside of the dwelling



09/4629

Table 11 Timber frame – insulation between studs and to exterior of sheathing board • Non-combustible products with the highest Euroclass A1 rating Timber studs filled with:

U-value 0.14—0.25


Earthwool DriTherm 32 Ultimate outside sheathing, thickness (mm)

Low-E service void • Products have an A+ generic Green Guide rating Typical U-values (W/m2K) • Very low U-values can be achieved 0.18 0.16 • No need for fire stopping (full fill) 0.23 0.19 • Partial fill system accepted by NHBC 0.19 0.16

Masonry outer leaf


140

50

90

50


140

50

90

50

0.24

0.20


140

50

0.20

0.17

90

50

0.25

0.21

Masonry outer leaf

Low-E service void

• Earthwool FrameTherm is compressible and friction fits between timber studs avoiding cold bridging at joints

Twin insulated – full fill Insulation thickness (mm)

Earthwool DriTherm 32 Ultimate outside sheathing, thickness (mm)


140

100

0.15

0.14

90

100

0.19

0.16


140

100

0.16

0.14

90

100

0.19

0.17


140

100

0.17

0.15

90

100

0.20

0.17

Timber studs filled with:


The following applies to Tables 8, 9, 10 and 11: Timber frame bridging factor of 15% to account for studs, noggins and sole plates etc. Stud depth is taken to be the same as the thickness of insulation specified. Thermal conductivity of timber studs is 0.12 W/mK. Ventilated low emissivity external airspace has an R-value of 0.29 m2K/W. Unventilated low emissivity external cavity has an R-value of 0.77 m2K/W. Service void has an R-value of 0.78 m2K/W.


Table 12 Solid masonry walls – external insulation 215mm solid block wall (λ = 0.150 W/mK)

215mm solid block wall (λ = 0.450 W/mK)

• Rock mineral wool product is a non-combustible product with the highest Euroclass A1 rating

plus insulation with the following λ values (W/mK): Insulation thickness (mm)

0.038

0.036

0.032

0.038

0.036

0.032


External Wall Insulation System U-value 0.14—0.34

12/4953

13/4999

• Compression resistant insulation provides a high level of support to the render • Lightweight and robust systems, advantageous where there are loading restrictions on the structure

180

0.16

0.16

0.14

0.18

0.18

0.15

160

0.17

0.17

0.15

0.20

0.20

0.17

140

0.19

0.19

0.17

0.22

0.22

0.19

130

0.20

0.20

0.18

0.23

0.23

0.20

• Efficient and quick to install

120

0.21

0.21

0.19

0.25

0.25

0.22

• Protects the fabric of the building

110

0.22

0.22

0.20

0.27

0.26

0.23

• Reduces thermal bridging

100

0.24

0.23

0.21

0.29

0.28

0.25

90

0.25

0.25

0.23

0.31

0.31

0.27

80

0.27

0.26

0.24

0.34

0.33

0.30

• Water repellent systems • Impact resistant solutions

U-values based on an internal finish of 12.5mm plasterboard (0.210 W/mK) on dot and dabs 0.038(W/mK) based on EWI Rock Slab and 0.032(W/mK) based on EWI EPS Slab.


17

Floor solutions Thermal performance The thermal performance of ground floors is determined by a combination of the thermal resistance of the floor construction, the shape of the floor and the insulation provided by the ground.


Table 13 Ground floor – insulation below slab or under screed Ratio of perimeter (m) to area (m2) 0.3

0.4

0.5

0.6

0.7

0.8


Insulation thickness (mm) Polyfoam ECO Floorboard Standard

U-value 0.12—0.22

170 (2 x 85mm)

0.12

0.13

0.13

0.14

0.14

0.14

150 (2 x 75mm)

0.13

0.14

0.15

0.15

0.15

0.16

130 (2 x 65mm)

0.14

0.16

0.16

0.17

0.17

0.18

100 (2 x 50mm)

0.17

0.19

0.20

0.21

0.21

0.22

• Long term exposure to water has negligible impact on the thermal performance of Polyfoam ECO Floorboard Standard • Can be used above or below the damp proof membrane (dpm)– above dpm Polyfoam protects dpm from damage before and during the concrete pouring process, below the dpm Polyfoam protects the dpm from possible puncture from hardcore and extremes of temperature at perimeter • Resists tough site conditions

No account has been taken for the thermal performance of the concrete slab or screed. The ground is assumed to be clay with a thermal conductivity of 1.50 W/mK.

• Industry leading compressive strength • Can tolerate traffic from subsequent trades without damage prior to floor finish being laid

Table 14 Ground floor – Insulation above slab Ratio of perimeter (m) to area (m2) 0.3

0.4

0.5

0.6

0.7

0.8

• Zero ODP and GWP rated product

Typical U-values (W/m K) 2


• Will accommodate slight imperfections in sub floor

Earthwool Thermal Floor Slab Plus

U-value 0.12—0.25

• Non-combustible product with the highest Euroclass A1 rating

210 (3x70mm)

0.12

0.13

0.14

0.14

0.14

0.15

• High compressive strength

170 (80+90mm)

0.14

0.15

0.16

0.17

0.17

0.17

• Easy handling and fitting

150 (70+80mm)

0.15

0.17

0.17

0.18

0.19

0.19

130 (60+70mm)

0.17

0.18

0.19

0.20

0.21

0.21

100

0.20

0.21

0.23

0.24

0.25

0.25

The U-values have been calculated assuming a clay subsoil with a thermal conductivity of 1.50 W/mK.


Table 15 Ground floor – Suspended beam and block floor with insulation below chipboard deck Ratio of perimeter (m) to area (m2) 0.3

0.4

0.5

0.6

0.7

0.8

• Structural and thermal solution



• Resistant to site damage

Polyfoam ECO Floorboard Standard

U-value 0.12—0.21

• Provides high thermal performance in limited insulation zone

170 (2 x 85mm)

0.12

0.13

0.13

0.13

0.14

0.14

150 (2 x 75mm)

0.13

0.14

0.14

0.15

0.15

0.15

130 (2 x 65mm)

0.14

0.15

0.16

0.17

0.17

0.17

100 (2 x 50mm)

0.17

0.18

0.19

0.20

0.21

0.21

• Robust and can tolerate traffic from following trades without damage prior to floor finish being laid

Concrete beams with aircrete blocks with a thermal conductivity of 0.15 W/mK. The ground is assumed to be clay with a thermal conductivity of 1.50 W/mK.

Table 16 Ground floor –Suspended beam and block floor with insulation below screed Ratio of perimeter (m) to area (m2) 0.3

0.4

0.5

0.6

0.7

0.8

• Provides high thermal performance in limited insulation zone

Typical U-values (W/m K) 2

Insulation thickness (mm) Polyfoam ECO Floorboard Standard

U-value 0.12—0.20

• Compression resistant, supporting screed under high point loads

• Structural and thermal solution

170 (2 x 85mm)

0.12

0.13

0.13

0.13

0.13

0.13

• Resistant to site damage

150 (2 x 75mm)

0.13

0.14

0.14

0.15

0.15

0.15

130 (2 x 65mm)

0.15

0.15

0.16

0.16

0.16

0.17

100 (2 x 50mm)

0.17

0.18

0.19

0.19

0.20

0.20

• Robust and can tolerate traffic from subsequent trades without damage prior to floor finish being laid

Concrete beams with aircrete blocks with a thermal conductivity of 0.15 W/mK. No account has been taken of the thermal performance of the screed. The ground is assumed to be clay with a thermal conductivity of 1.50 W/mK.


19

Floor solutions (continued)

Table 19 Ground floor – Suspended timber floor with insulation between joists Ratio of perimeter (m) to area (m2) 0.3

0.4

0.5

0.6

0.7

0.8

• Earthwool Loft Roll is manufactured to suit standard joist spacing’s

Typical U-values (W/m2K) 0.13

0.13

0.14

0.14

0.14

0.14

250 (150+100mm)

0.14

0.15

0.15

0.16

0.16

0.16

• Products friction fit between joists avoiding cold bridging at the joints

200 (2x100mm)

0.16

0.17

0.17

0.18

0.18

0.18

• Low cost solution

150

0.19

0.20

0.21

0.22

0.22

0.23

• Fast and simple solution


250 (150+100mm)

0.14

0.14

0.15

0.15

0.15

0.15

200 (2x100mm)

0.16

0.17

0.17

0.18

0.18

0.18

150

0.19

0.20

0.21

0.22

0.22

0.23

250 (100+75+75mm)

0.13

0.14

0.14

0.14

0.14

0.15

200 (2x100mm)

0.15

0.15

0.17

0.17

0.17

0.18

140

0.19

0.20

0.21

0.21

0.22

0.22


300 (2x150mm)

Earthwool Flexible Slab



U-value 0.13—0.23

The U-values have been calculated assuming 48mm wide joists at 600mm centres.

Table 17 Exposed upper floor – Insulation below concrete soffit – Earthwool Beam and block Insulation thickness (mm)

Dense

Medium

Earthwool Soffit Linerboard Standard

• Aesthetic finish Precast concrete Cast slabs Lightweight Aircrete plank (150mm) (200mm) • Installed from below so no access to area above floor required Typical U-values (W/m2K) • Fully non-combustible solution • Highest Euroclass A1 rating

165/6

0.20

0.20

0.20

0.19

0.20

0.20

130/6

0.25

0.25

0.25

0.23

0.25

0.25

• Can enhance acoustic performance of floor

U-value 0.19—0.25

Table 18 Exposed upper floor – Insulation between timber joists • Non-combustible products with the highest Euroclass A1 rating

Typical U-values (W/m2K) Insulation thickness (mm)


0.33*

0.25*

0.26*

300

0.15

0.15

0.15

250

0.17

0.18

0.18

200

0.21

0.21

0.21

• Products friction fit between joists avoiding cold bridging at the joints

150

0.26

0.27

0.27

• Low cost solution

• Earthwool Loft Roll is manufactured to suit standard joist spacing’s

• Fast and simple solution

U-value 0.13—0.27

Earthwool Flexible Slab

300

0.13

0.13

0.13

250

0.15

0.16

0.16

200

0.19

0.19

0.19

150

0.24

0.24

0.24

*Additional thermal resistance for shelter effect of enclosed unheated spaces, Ru (m2K/W). The U-values have been calculated assuming joists are 48mm wide, spaced at 600mm centres and the same depth as the insulation.


How Knauf Insulation can help Technical Support Our Technical Support Team (TST) provides personal, high level technical support which includes our experienced team of advisors supplying U-value calculations, condensation analysis, SAP calculation assistance and assistance with CAD drawings and NBS clauses. Also available through the TST is the 3D finite element heat loss calculation service. For further information please call the TST on 01744 766666. 3D heat loss calculation service Our Technical Support Team have the ability to provide 3D finite element heat loss calculations to fully comply with Part L of the Building Regulations. By analysing the heat flows through external wall construction elements (such as rainscreen cladding systems) TST can provide robust supporting evidence for U-value calculations. For further information please call TST on 01744 766 666.

BBA/TIMSA U-value Competency Scheme Knauf Insulation is a fully accredited member of the prestigious and industry leading British Board of Agrément (BBA) U-value and Condensation Calculation Competency Scheme.

The scheme aims to promote and assist accurate, objective and consistent calculation of U-values and condensation analysis within the UK construction industry. As a result, Knauf Insulation customers can be assured that the U-value and condensation calculations supplied to them (and contained in this publication) are in line with all relevant industry standards, accurate and consistent, and there is a clear and comprehensive audit trail in place.

Project and Specification Managers Knauf Insulation has a team of Business Development Managers and Project and Specification Managers covering all parts of the country. Their role is to provide cost-effective solutions to specifiers of thermal insulation, acoustic insulation and fire protection. For more information please visit www.knaufinsulation.co.uk

Building Information Modelling (BIM) Knauf have been leading a major delegation across Europe and the US on BIM for several years. We believe that the use of BIM will increase very quickly in the UK as its use will be compulsory on all Government funded projects by 2016. At Knauf Insulation we are fully committed to providing our customers with a complete range of specification support documentation including Building Information Modelling (BIM) materials and material layer sets (BIM Objects). We have produced a comprehensive library of BIM Objects to support the specification community and have ensured that they are readily available and compatible with a wide range of software programs including, Revit, ArchiCAD, Bentley and Vectorworks. In addition to providing BIM enabled objects and material layer sets we have also started a funded project working in collaboration with numerous market leading organisation’s in order to manage a pilot scheme. The deliverable will be a case study for Government and a training scheme for 500+ individuals looking to develop BIM skills with a qualification recognised at NVQ level. This is a very exciting project and one that is being looked upon as vital to ensuring buy-in from all organization`s involved. Details of this program are available upon request. For our full BIM library please visit www.knaufinsulation.co.uk/bim

Glossary of terms Approved Construction Details Approved Construction Details (ACDs) are details of junctions at openings at junctions between elements (such as a wall/floor junction) which have been formally recognised by the Department of Communities and Local Government. The details focus specifically on measures to minimise thermal bridging and air leakage, and each detail has an approved linear transmittance value which is listed in Table K1 of SAP 2012. They include a check list for recording compliance.

DER The Dwelling Emission Rate (DER) is the CO2 emission rate for the proposed dwelling. It is expressed in terms of kg/m2/yr. In practice, two DER calculations are needed; the first at the design stage, based on plans and specifications used in the submission to the Building Control and the second at the final stage of completion. The final calculation should be based on the dwelling as constructed, including any changes made since the design stage and the results of the air permeability test.

EPBD The objective of the European Union Energy Performance Building Directive (EPBD) is to “promote the improvement of energy performance of buildings within the Community taking into account outdoor climatic and local conditions, as well as indoor climate requirements and cost-effectiveness.” All member countries must implement the Directive which has been updated in 2010. England is complying with the Directive through the application of Approved Document L and the requirement to issue Energy Performance Certificates.

Fuel factor The fuel factor is used when calculating the Target Emission Rate (TER). The fuel factor takes into account the higher carbon emissions of fuels other than mains gas and is applied where the main form of heating for the proposed dwelling is not mains gas. The fuel factor has the effect of penalising fuels other than mains gas for the proposed dwelling. Where heating or hot water is to be provided by appliances having different fuels, the fuel used for the main heating system should be used in the TER calculation.

The fuel factors are to be reviewed as progress is made towards zero carbon. In particular, where grid electricity is used for heat pumps, the fuel factor for heat pumps will be reviewed as the renewable heat incentive is introduced. The solid mineral fuel factor should be used where the appliance can only be used for that fuel, or where a solid multi-fuel appliance is being used in a Smoke Control Area. The solid multi-fuel fuel factor should only be used where the appliance is designed for that purpose and, in a Smoke Control Area, where the specific appliance has been approved for that use.

TER The Target CO2 Emission Rate (TER) is the energy performance target that must be achieved by the proposed dwelling to comply with the requirements of the Approved Document. It is expressed in terms of kg/m2/yr. For the 2006 edition of the Approved Document, the TER represented a 20% improvement over the calculation for the ‘notional dwelling’ with a 2002 specification. For the 2010 edition, the requirement is to make a further 25% saving over the 2006 TER, in effect making a 40% saving over the 2002 ‘notional dwelling’.

Notional dwelling

TFEE`s

The ‘notional dwelling’ is the benchmark dwelling design from which the Target Emission Rate (TER) is determined. It is of the same size and shape as the proposed dwelling constructed to the reference values detailed in Appendix R of SAP 2012. For the notional dwelling, the party wall heat loss is taken to be zero.

The Target Fabric Energy efficiency Standard (TFEE) accounts for a dwelling’s combined, annual heating and cooling load for which a limit is set by SAP based on the performance of a notional dwelling of the same size and shape as that being assessed, but with fixed values for the fabric performance e.g. U-values, thermal bridging, air leakage etc, a 15% margin is then added, giving the designer some additional design flexibility.

Robust Details Previously, there were Robust Details for thermal and sound insulation. Those for thermal insulation became Approved Construction Details but those for sound insulation retained the Robust Details title. The Robust Details scheme provides an alternative to pre-completion testing for demonstrating compliance with the sound insulation performance standards of Part E of the Building Regulations for new dwellings.

SAP 2012 The Government’s Standard Assessment Procedure (SAP) is the method that must be used for calculating the CO2 emission rate and Target Fabric Energy Efficiency Standard for new dwellings. It calculates the energy requirement for heating, hot water, ventilation and internal lighting for the dwelling. As well as giving the CO2 emission rate in terms of kg/m2/yr, it also produces a SAP rating, on a scale from 1–100. The SAP 2012 includes all the technical assumptions and rules for calculating the CO2 emission rate and it includes the SAP worksheet. Software versions of the SAP calculation method are available from a number of sources.

TFEE equates to the amount of energy consumed in kilowatt-hours per square metre of floor area per year.

Energy Performance Certificates Energy Performance Certificates for New Build Dwellings The Energy Performance of Buildings Directive (EPBD) is a crucial legislative component of the energy efficiency activities of the European Union designed to meet the Kyoto commitment and respond to issues raised in the Green Paper on energy supply security. The Directive applies minimum requirements on the energy performance of buildings and their energy performance certification through the introduction of Energy Performance Certificates (EPCs). The requirement for EPCs for new build houses came into force in April 2008.

The impact and content of EPCs It is compulsory for EPCs to be provided before a property in England and Wales can be put on the open market for sale with vacant possession. Energy Performance Certificates tell you how energy efficient a home is on a scale of A-G. The most efficient homes – which should have the lowest fuel bills – are in band A.

In addition, the Certificate also tells you, also on a scale of A-G, about the impact the home has on the environment. Better-rated homes should have less impact through reduced carbon dioxide emissions. The average property in the UK is in bands D-E for both ratings. The EPC includes recommendations on ways to improve the home’s energy efficiency to save you money and help the environment. Sellers of newly built homes will have to provide a predicted assessment of the energy efficiency of the property, but a full EPC should be provided to the buyer when the home is completed.

Qualifications to produce EPCs To protect consumers, EPCs must only be produced by accredited assessors who are suitably qualified or competent to produce energy assessments.

Energy Performance Certificate

“Suitably qualified” refers to an individual having either a qualification or approved prior experience and learning equivalent to the National Occupational Standard requirements relevant to the specific occupation for which the individual seeks accreditation. In addition, to be an Energy Assessor, an individual must be a member of an Accreditation Scheme.


23

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April 2014

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Thermal Efficiency Standards in New Dwellings

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