Sci p3861 Code for Sustainable Homes by Fusion Building Systems

P386 Code for Sustainable Homes: How to satisfy the code using steel technologies

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Code for Sustainable Homes: How to satisfy the code using steel technologies

Sustainability

P386 Code for Sustainable Homes: How to satisfy the code using steel technologies

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The world’s tallest modular building, Paragon, West London

The Code for Sustainable Homes provides an environmental assessment methodology for certifying the performance of new homes in England and Wales. It encourages a ‘step change’ in building practice that includes energy efficiency as a key element. Buildings are rated on a scale from Level 1 to Level 6, where Level 6 is the highest. Since May 2008 it is mandatory for all new homes to be rated (not necessarily assessed) against the Code. Buildings that are not assessed under the Code are awarded a ‘nil-rated’ certificate. Minimum standards for energy and water efficiency are set for every Code level, with minimum standards for Level 1 compliance set above current (2006) Part L Building

Berkeley First and Caledonian Building Systems

Regulation requirements. Code Level 6 corresponds to zero carbon in building operation and is foreseen as the target for the Regulations in 2016. The challenge facing the construction industry in the residential building sector is how to achieve the higher levels of Code compliance, which includes all aspects of energy and water efﬁciency, materials selection, waste, health and well-being of occupants, building management and site ecology. The same or similar requirements are likely to be applied in the future to the non-housing sector.

the targets are arguably the most challenging. This publication therefore focuses on this aspect of the Code and how steel construction can be used to meet the energy and CO2 emissions targets for Code Levels 3 and 4 compliance. Steel framing systems are commonly used to construct residential buildings. Steel systems offer many sustainability beneﬁts, over and above the criteria assessed under the Code.

Of the nine assessment categories in the Code for Sustainable Homes, ‘Energy and CO2 emissions’ has the highest weighting and

Front cover images: Top left - MoD military accommodation, Corus Living Solutions. Top right - Paragon, West London, Berkeley First and Caledonian Building Systems. Bottom left - Residential apartments, Glasgow, Metsec. Bottom right - Debut housing by Redrow, Fusion Building Systems.

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Code for Sustainable Homes: How to satisfy the code using steel technologies This publication explains the Code for Sustainable Homes and demonstrates how Code Levels 3 and 4 can be readily achieved using steel construction.

Contents Introduction

Most of the assessment criteria included in the Code are not directly related to the building structure and therefore the focus of this publication is on the energy and CO2 emissions requirements of the Code. SAP (Standard Assessment Procedure) results of typical steel residential buildings that comply with Code Levels 3 and 4 are presented and guidance is given on how to achieve highly insulated and airtight steel-based building envelopes that minimise thermal bridging.

Energy and carbon dioxide emissions targets

Achieving energy and carbon dioxide emissions targets

Design and construction guidance for energy efﬁciency

The technologies described can also meet the CO2 emissions targets for Code Levels 5 and 6. However, at these levels, the emphasis shifts from the efficiency of the building envelope to the provision of LZC (Low and Zero Carbon) technologies. Therefore, the scope of this publication has been limited to achieving compliance with the Code by optimising the efficiency of the building fabric. Reflecting the growing importance of materials selection and use in construction, guidance is also given on compliance with the materials category of the Code. The credentials of steelbased systems are described.

Materials

Other Code assessment categories

Code assessment for a medium-rise residential building

Appendix A

References

A full Code assessment of a steel framed, medium rise apartment building is presented to illustrate the routes to achieving compliance with Code Levels 3 and 4 that can be anticipated with this form of construction.

The Steel Construction Institute is the leading, independent provider of technical expertise and disseminator of best practice to the steel construction sector. We work in partnership with clients, members and industry peers to help build businesses and provide competitive advantage through the commercial application of our knowledge. We are committed to offering and promoting sustainable and environmentally responsible solutions. www.steel-sci.org

Steel Homes Group develops and promotes the effective use of steel in residential construction. Its core values are: To advance the use of steel products and systems in residential construction. ●

To be a professional and authoritative voice for industry and to present a rigorous, positive and united image of the value of steel in residential construction to occupiers, owners, other stakeholders and their representative bodies. ●

To act as the guardian of quality standards on behalf of clients and users by putting in place appropriate industry standards that are focused on the needs of owners and occupiers, while meeting the needs of wider stakeholders. ●

www.steelhomesgroup.com

The Zero Carbon Hub is pleased to have engaged with the Steel Construction Institute to present a series of solutions in order to achieve Code levels 3 and 4 using steel frame construction. About the ZERO CARBON HUB BACKGROUND The Zero Carbon Hub is a non-proﬁt company limited by guarantee. We are a public/private partnership established to take day-to-day operational responsibility for co-ordinating delivery of low and zero carbon new homes. The Callcutt Review of House-building Delivery identiﬁed the need for this new venture and more than 25 organisations were consulted before the Zero Carbon Hub was launched on 28 June 2008. The Zero Carbon Hub supports and reports to the 2016 Taskforce which was established in January 2007 and is chaired

by the Housing Minister and the Executive Chairman of the Home Builders Federation. PURPOSE To facilitate the mainstream delivery of low and zero carbon homes home. We will fulfil this purpose by monitoring, coordinating and guiding the zero carbon programme and engaging organisations active in low and zero carbon homes. To do this we are developing five integrated workstreams; Building energy efficiency, Energy supply, Examples and scale up, Skills and training and Consumer engagement. KEY STRATEGIC OBJECTIVES ● Provide leadership and create confidence ● Reduce risk and clear obstacles ● Disseminate information www.zerocarbonhub.org

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Introduction to the Code for Sustainable Homes The Code for Sustainable Homes [1] is a national standard for use in the design and construction of new homes. The Code is based on, but supersedes, EcoHomes. It was launched in December 2006, became operational in England in 2007 and, since May 2008, it is mandatory for new homes to have a Code rating. Note: It is not mandatory for buildings to be assessed under the Code.

Implementation of the Code is managed by BRE Global who, on behalf of the Department of Communities and Local Government, train and license Code assessors.

The Code for Sustainable Homes is based on 34 environmental criteria that are grouped together under the nine categories shown in Table 1. Credits achieved are summed and the total category score weighted, using the factors in Table 1. Weighted category scores are then added together to give the overall score out of 100. Table 2 gives the total score required for compliance with each of the six Code Levels. It is a requirement of the Code that buildings are assessed at the design stage and veriﬁed through a post-construction review.

Debut housing by Redrow, part of ‘Design for Manufacture’ initiative

Final Code compliance certiﬁcates are only issued after the post-construction assessment has been carried out. The Code sets minimum mandatory standards for CO2 emissions, indoor water use, materials, waste and surface water run-off for compliance with all levels of the Code (see Table 3). In addition, demanding mandatory standards for CO2 emissions rates are required to achieve Code Levels 1 to 6 (see Table 5).

Fusion Building Systems

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INTRODUCTION

Table 1: Code categories, credits, weightings and points Code category

Credits available

Weighting factors (%)

Maximum Code points achievable

1 Energy and CO2 emissions

36.4

2 Water

9.0

3 Materials

7.2

4 Surface water run-off

2.2

5 Waste

6.4

6 Pollution

2.8

7 Health and well-being

14.0

8 Management

10.0

9 Ecology

12.0

Total

104

100

Table 2: Overall score required for different levels of Code compliance Code Level

Total Code points required

Comparison with other standards

Above Part L (2006) standards Similar to EcoHomes PASS level

Similar to EcoHomes GOOD level

Similar to EcoHomes VERY GOOD level

Current exemplary performance

Aspirational standard based on zero carbon emissions

Table 3: Minimum mandatory standards for Code compliance Code category

Minimum requirement (all code levels)

CO2 emissions

See Table 5

Indoor water use

Code Level

Maximum indoor water consumption (litres/person/day)

1 and 2

120

3 and 4

105 80

5 and 6 Materials

At least 3 of the following 5 key elements of the building envelope to achieve the ‘Green Guide to Specification (2008)’ ratings of A+ to D: ● Roof ● External walls ● Internal walls ● Upper and ground floors ● Windows

Waste

Provision of non-recyclable waste storage. Construction Site Waste Management Plan.

Surface water run-off

The peak run-off into watercourse should be no greater for the development site than it was for the pre-development site.

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Energy and carbon dioxide emissions targets Of the nine Code categories, the Energy and CO2 emissions targets are the most highly weighted and the most challenging. The Energy and CO2 emissions category attracts 36% of the available Code points. The Energy and CO2 emissions category includes the nine issues shown in Table 4. Ene 1 is the most significant issue with 15 credits and is defined by the percentage that the Dwelling CO2 Emissions Rate (DER) is below the Target CO2 Emissions Rate (TER).

This is a key performance indicator for which there are minimum mandatory requirements

Seafront apartments, Scarborough

for compliance at each Code level (see Table 5) and is the criterion that is most influenced by the choice of the construction technology. The TER is the maximum allowable CO2 emissions rate that is compliant with Building Regulations Approved Document L1A (2006) [2]. The DER is the predicted annual carbon dioxide emissions rate from the energy used in heating, cooling, hot water and lighting. The TER and DER are calculated using SAP (see Table 6).

Metsec

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ENERGY AND CARBON DIOXIDE EMISSIONS TARGETS

Table 4: Energy and CO2 emissions issues Issue

Detail

Credits available

Code points available

Ene 1

Dwelling Emissions Rate (DER) (% improvement relative to Part L TER)

18.8

Ene 2

Reducing the building heat loss parameter

2.5

Ene 3

Energy efﬁcient internal lighting

2.5

Ene 4

Provision of clothes drying space

1.3

Ene 5

A+ energy rated white goods

2.5

Ene 6

Energy efﬁcient external lighting

2.5

Ene 7

Provision of low or zero carbon (LZC) technologies

2.5

Ene 8

Provision of cycle storage facilities

2.5

Ene 9

Provision (space and services) for home working

1.3

36.4

Total

Table 5: Mandatory requirements for CO2 emissions (issue Ene 1) Code level

% improvement of DER over TER

Code points

Likely minimum regulatory requirement1

10%

1.25

18%

3.77

25%

6.28

2010

44%

10.04

2013

100%

17.57

18.83

2016

140%

It is intended that the Code should ‘signpost’ future requirements of the Building Regulations, in this case Part L. Although the precise requirements of future changes to Part L are not known, at the time of writing, these dates give the proposed trajectory for improvement towards the Government’s goal of zero carbon new homes by 2016. 2

Code Level 6 requires 140% improvement over the TER. This is because Code Level 6 requires zero net carbon from all energy used in the dwelling, whereas Part L compliance is only based on ‘regulated’ energy use that excludes cooking, appliances, etc.

SAP 2005 The Government’s Standard Assessment Procedure (SAP) [3] is the approved methodology for rating the energy performance of dwellings. SAP ratings are used to demonstrate compliance with Part L1A of the Building Regulations (2006), to calculate Energy Performance Certiﬁcate

ratings for new homes and for compliance with Code issue Ene 1. The current version of the assessment software is SAP 2005. Key input parameters for SAP are the U-values of the external envelope and values associated with thermal bridging, air tightness and ventilation as summarised in Table 6.

Together with the geometry of the building, these inputs deﬁne the heat loss parameter (HLP) for the dwelling, which in combination with the services solution (space heating, water heating) provide an estimate of the operational CO2 emissions from the dwelling, or DER.

Table 6: Basic envelope parameters for SAP calculations Parameter

Description -2

-1

U-value (Wm K )

A measure of the thermal transmittance of the construction envelope. The heat in Watts passing through a square metre of building fabric per degree of temperature difference from the inside to outside.

y-value (Wm-2K-1)

A measure of the total heat loss due to linear thermal bridging. This is given as the heat lost in Watts per square metre of exposed surface area per degree of temperature difference from the inside to outside.

Air tightness (m3h-1m-2)

This is a measure of the air leakage of the building. It is defined as the volume of air that must be pumped into the building per hour per square metre of exposed surface to maintain a pressure of 50 Pa. This is not the same as the natural air infiltration rate under normal working conditions, which will be much less.

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Achieving energy and carbon dioxide emissions targets

To assess the operational energy performance (and associated CO2 emissions) of steel framed residential buildings, SAP (2005) assessments have been carried out on two typical buildings: End terrace or semidetached house

Two-storey house, with a pitched, warm roof (to allow the use of the roof space). Long axis aligned East/West and plan dimensions of 6 by 8 m, giving total floor area of 96 m2.

Mid-side apartment

4-storey residential building comprising two apartments per stairwell. Internal dimensions are approximately 7 by 9 m with the long axis orientated North/South, giving a total floor area of 63 m2 per apartment.

For both buildings, the performance of the building fabric has been incrementally improved to achieve the CO2 emissions reductions necessary to achieve the mandatory Code Level 3 and 4 requirements, i.e. 25% and 44% improvement in the DER respectively (see Table 5). Where necessary, low and zero carbon (LZC) technologies have also been modelled in the SAP assessment. Fabric improvements modelled included; improved U-values, greater airtightness and reduced linear thermal bridging. A summary of the SAP modelling assumptions, the results achieved and the fabric specification improvements required to achieve Code Levels 3 and 4 compliance for the DER (Ene 1) are given in Appendix A.

It should be noted that the compliant specifications developed are intended only for guidance. For example where an external wall U-value of 0.2 Wm-2K-1 has been used to achieve Level 3 compliance, this does not mean that it is impossible to achieve Level 3 with a higher U-value. Every dwelling and SAP calculation is unique, and the DER depends on a wide range of factors. SCI’s results have been reviewed together with those generated by the Energy Saving Trust [4], The Concrete Centre [5] and others. The studies are consistent, yielding similar indicative specifications (see Table 7) to meet the Ene 1 targets for Code Levels 3 and 4 compliance.

To achieve Code Level 4, however, it is likely that both a highly efficient building envelope and some form of LZC technology will be required.

Table 7: Indicative speciﬁcations to meet DER targets for Code Level 3 and 4 compliance Building Regulations 2006

Code Level 3 Fabric improvements only

Code Level 3 also with renewables

Code Level 4

- External wall

0.25 - 0.3

0.2 - 0.25

0.2

- Ground floor

0.2 - 0.25

0.15 - 0.2

0.15

0.1 - 0.13

- Windows/doors

1.8 - 2

1 - 1.2

1.5

0.8 - 1

Thermal Bridging y-value (Wm-2K-1)

0.08

0.04

0.08

0.04

Air Permeability (m3h-1m-2 @ 50Pa)

7 - 10

2-3

Ventilation Solution

Natural

MVHR*

Natural

MVHR*

None

e.g. Solar Thermal or PV

U-Values (Wm-2K-1)

- Roof

Renewable Energy Technologies

* Mechanical Ventilation with Heat Recovery

Broadly the conclusions are that, with a highly energy efficient building envelope and mechanical ventilation with heat recovery (MVHR), it is possible to achieve Code Level 3 compliance (Ene 1) without the need for LZC technologies. If renewable energy generation is included, within the development or an individual building, this can be ‘traded off ’ against the envelope specifications, i.e. the envelope specification can be relaxed. In reality, such decisions may be made on cost grounds or are influenced by other factors such as planning conditions.

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Design and construction guidance for energy efficiency

Steel construction systems can achieve high levels of energy efficiency by minimising fabric heat losses and improving the air-tightness of the building envelope. In this section, guidance is provided to justify the parametric assumptions used to achieve compliance with the energy efficiency (Ene 1) requirements of Code Levels 3 and 4 (see Appendix A). Specific guidance is given on how to achieve the required U-values and air-tightness for Code compliance, while minimising thermal bridging using steel-based systems.

Table: 8 Insulation thickness – Brick cladding Multi-storey buildings

U-values – external walls U-values are presented for two generic, steel-based cladding systems (see illustrations below): ● ●

Brickwork cladding on light steel framing. Insulated render supported on light steel framing.

For each system, U-values have been calculated using the BRE-approved software Build U 3.2.6. This software package uses the simplified calculation method set out in Doran and Gorgolewski [6], which is based on BS EN ISO 6946 [7] with some important differences to allow for cold bridging across insulated layers, and has been validated using procedures in BS EN ISO 10211-1 [8]. The calculations have also been carried out in accordance with Anderson [9].

Table 8 shows the U-values achieved using varying thickness of external insulation in the brick clad wall. The results demonstrate that the external wall U-value requirements for Code Levels 3 and 4 compliance are easily achieved using brickwork cladding on light steel framing. As for the brickwork option, the effect of increasing the thickness of external insulation in the insulated render system has been modelled to achieve the U-values shown in Table 9. The results demonstrate that the external wall U-value requirements for Code Levels 3 and 4 compliance are easily achieved using an insulated render system on light steel framing.

Table 9: Insulation thickness – Insulated render cladding

Housing

U-Value (Wm-2K-1)

Thickness of Insulation Board (mm)

Overall Wall Thickness (mm)

U-Value (Wm-2K-1)

Thickness of Insulation Board (mm)

Overall Wall* Thickness (mm)

U-Value (Wm-2K-1)

Thickness of Insulation Board (mm)

Overall Wall Thickness (mm)

0.35

45+

322+

0.35

45†

297†

0.35

160

0.25

312

0.25

297

0.25

185

0.20

337

0.20

317

0.20

210

0.15

100

377

0.15

105

357

0.15

120

250

This example has no insulation between the 100 mm deep C sections.

* Housing applications use 75 mm deep C sections. † This example has no insulation between the 75 mm deep C sections.

Data for polyurethane insulation board (PUR).

1 or 2 layers of 12.5 mm fire resistant plasterboard

2 layers of 12.5 mm fire resistant plasterboard

Light steel sections (100 mm deep at 600 mm centres)

Mineral wool insulation Rigid PUR insulation board

Mineral wool insulation

Light steel sections (100 mm deep at 600 mm centres)

Cement particle sheathing board

Stainless steel wall ties fixed to C sections through PUR insulation

Rigid insulation board

Breather membrane

Polymer modified render

Brick external cladding

Brick cladding attached to light steel framing

Insulated render cladding attached to light steel framing

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DESIGN AND CONSTRUCTION GUIDANCE FOR ENERGY EFFICIENCY

Air tightness

Part L (Conservation of fuel and power) of the Building Regulations requires that buildings achieve reasonable levels of airtightness to reduce cold air infiltration and to reduce unnecessary heat losses. Part F (Ventilation) aims to encourage building ventilation to maintain good indoor air quality and to minimise condensation risk. In effect therefore a balance is required between uncontrolled infiltration, leading to heat loss, and controlled ventilation enhancing indoor air quality. At air permeabilities of less than 3 to 4 m3h-1m-2, some form of mechanical ventilation is required to maintain good indoor air quality and to minimise condensation risk.

An air permeability of 10 m3h-1m-2 (expressed over the exposed envelope area and at the air-tightness test pressure differential of 50 Pa) is currently considered, in Part L (2006), to be a sensible maximum for general building construction. However, achieving even this value requires a reasonable level of quality control on site. Part L1A (2006) requires mandatory air pressure testing of a proportion of dwellings within a new development to demonstrate that the air permeability specified in the SAP assessment has been achieved. It is recognised that off-site manufacture, such as the use of modular construction, can lead to more reliable and lower air permeability levels, especially when external sheathing

boards or membranes are included in the manufacture of the panels of modules. Achieving low air permeabilities requires a range of measures, some related to design and detailing, and others to installation practice. For light steel framed construction, normal practice should lead to airpermeabilities of 5 to 7 m3h-1m-2, and for modular construction, the equivalent figure would be 3 to 4 m3h-1m-2. Table 10 summarises the range of measures that may be considered to reduce air permeability in practical applications, drawing a distinction between essentially site-based construction and off-site construction. In many ways, the details required for good acoustic insulation and fire resistance, also provide more effective air-tightness.

Table 10: Construction practice to achieve various levels of air-tightness Air-permeability Target

Light Steel Framing (Planar Construction)

Modular Construction (Volumetric Units)

< 10 m h m

Normal construction practice compliant with Part L1A of the Building Regulations.

Modular construction achieves improved air-tightness, at much less than 10 m3h-1m-2

< 7 m3h-1m-2

Seal joints and gaps at top and bottom of walls using acoustic sealant. Seal external insulation boards. Use ‘socket pads’ to seal around service penetrations.

Modular construction achieves this level of air-tightness due to precise cutting of boards and sealants at junctions.

< 5 m3h-1m-2

Use external sheathing boards plus the above measures to improve air-tightness. Vapour-check plasterboards may be used internally. Use sleeves around pipes at the airing cupboard to roof space junction.

Modular construction often uses external rigid sheathing boards and double layers of plasterboards internally, combined with quality-controlled manufacture of the modules.

< 3 m3h-1m-2

Special measures may be required including the following techniques: ● Sheathing boards externally ● Vapour-check plasterboard internally ● Double layer service void internally ● Mechanical ventilation is required to maintain air quality.

Modular construction can achieve this level of performance by sheathing boards and sealing around all service penetrations (due to the cellular nature of the construction system).

< 2 m3h-1m-2

An impermeable continuous membrane may be required to minimise air leakage. Mechanical ventilation is required.

The performance of modular construction is more reliable and less dependent on site installation. A membrane sealant may be provided in the manufacture of the modules.

3 -1

-2

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Control of Thermal Bridging Thermal bridging may occur at the junction of two or more building elements, where the building structure changes, e.g. at a corner, or where the continuity of the building fabric is broken by the penetration of an element.

Repeating thermal bridges occur at regular intervals over the building envelope, e.g. wall ties, and are accounted for in the U-value calculation for the element, in this case, the wall. Non-repeating or linear thermal bridging occurs mainly at the junction of two construction elements, for example the junctions of floor and wall, or wall and roof eaves. In SAP 2005, there are two ways of calculating the heat loss from linear thermal bridging.

The first of these involves calculating the linear thermal transmittance for every thermal bridge, known as the ψ-value (units of Wm-1K-1). These bespoke ψ-values are then multiplied by the length (l) of the detail concerned in the dwelling to give the overall heat loss from thermal bridging, HTB so that: HTB = Σi (li x ψi). The second method assumes a y-value (Wm-2K-1) for the entire dwelling such that: HTB = y × Aexp where Aexp is the total exposed area of the dwelling. If all construction details comply with the Accredited Construction Details (ACDs) checklist then a y-value of 0.08 Wm-2K-1 may be used in the SAP 2005 assessment.

In 2008, the Energy Saving Trust (EST) published a series of Enhanced Construction Details (ECDs) and associated guidance for their use within SAP 2005. EST research indicated that reduced y-values can be used as long as the ψ-values of lintels, groundfloor/wall and gable/ceiling junctions are limited to 0.07 Wm-1K-1. Therefore if ECDs are used for these junctions and all remaining details are ACDs, or better, a y-value of 0.04 Wm-2K-1 can be used in SAP 2005. Further information on ECDs, including the light steel frame ECDs, are available from the Energy Saving Trust [11]. The detail below shows an ECD for a typical ground floor/wall junction using light steel framing.

Further detail on ACDs is available via the Government’s Planning Portal [10].

External wall – 50 mm minimum cavity Closed cell insulation board (70 mm minimum thickness) Mineral wool insulation (70 mm minimum) Vapour control/air barrier lapped to damp-proof membrane 12 mm fire resistant plasterboard 12 mm plasterboard Services zone

Damp proof membrane/ air barrier

EPS insulation

Screed

Floor boarding

> 300 mm overlap of insulation Beam and block floor Blockwork (thermal conductivity < 0.19Wm-1K-1) Membrane Foundation

Enhanced Construction Detail for steel-framed ground floor/wall junction. Enhanced Detail SF01-F01 (A)[11]

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Materials There is growing awareness of the environmental impact of construction materials and of the need for their robust assessment. Under the Code, construction materials are assessed using the three criteria shown in Table 11. Table 11: Code Material assessment issues Issue ID

Description

Credits available

Maximum Code points available

Mat 1 Mat 2

Environmental impact of materials

4.5

Responsible sourcing of materials Basic building elements

1.8

Mat 3

Responsible sourcing of materials Finishing elements

0.9

Infill walling in a structural steel frame, Slimdek

Environmental impact of materials (Mat 1) The following building elements are assessed using the Green Guide to Specification [12] ratings: ● ● ● ● ●

Roof External walls Internal walls (including separating walls) Upper and ground floors (including separating floors) Windows.

Green Guide ratings are derived using BRE’s Environmental Profiles [13] life cycle assessment methodology. Under this approach, 13 different environmental impacts are normalised, weighted and aggregated to give a single score in Ecopoints. This score is then converted to an A+ to E rating, where A+ is the best and E the worst score within a certain product category.

The Green Guide ratings take account of all environmental impacts including mining, processing, transport, waste, product replacement intervals, maintenance and end-of-life impacts including recycling and landfill. Under the Code, credits are awarded according to the Green Guide rating as shown in Table 12.

Table 12: Credits awarded for different Green Guide ratings Green Guide rating

Credits per building element

A+ rating

A rating

B rating

C rating

0.5

D rating

0.25

E rating

0 Light steel framing

Fusion Building Systems

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Materials

MoD military accommodation which achieved BREEAM Excellent

Corus Living Solutions

Steel-based systems score well under the Green Guide to Specification. Table 13 provides the latest (2008) Green Guide ratings for a range of typical residential steel-based specifications. Table 13: Green Guide ratings for light steel residential specifications BRE Green Guide Rating

Form of Construction Framework: Separating wall using light steel framing, glass wool insulation and plasterboards Chipboard decking on light steel floor joists and plasterboard ceiling OSB decking on light steel floor joists and plasterboard ceiling

Composite floor slab on steel decking with resilient surface and OSB board with plasterboard ceiling Cladding:

Brickwork on light steel insulated external wall Terracotta rain-screen on light steel insulated external wall

A A A+ A A+ A

Semi-automated production line at Corus Living Solutions' factory

Responsible sourcing (Mat 2 and 3) Responsible sourcing of basic building elements is assessed based on a tiered scoring system that is tailored to specific materials and supply chains. Credits are awarded based on the proportion of ‘responsibly sourced’ materials within the following key elements of the building:

a certified environmental management system (EMS), e.g. ISO 14001 or EMAS. This applies both to steel production and for finishing, e.g. fabricating or roll-forming steel construction products.

Frame Ground floor Upper floors (including separating floors) Roof External walls Internal walls (including separating walls) Foundation/substructure (excluding sub-base materials) Staircase.

Steel is a global commodity. The World Steel Association, which represents the major international steel producers, disseminates KPIs (Key Performance Indicators) for the global steel production industry. In its most recent report [14], WSA reported that over 85% of steel production facilities are certified to a registered international environmental management system standard. In the UK, all of Corus’s sites are certified to the EMS standard ISO 14001.

For steel products and systems, compliance is demonstrated by specifying products that have been produced by companies that have

In addition, many of the leading manufacturers of steel construction products are certified to ISO 14001.

● ● ● ● ● ● ●

●

Modular housing, South Chase, Harlow is efficient in materials use. FutureForm and Ayrshire Framing

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Other Code assessment categories The remaining seven Code assessment categories are not directly related to the choice of the building construction technology. Table 14 gives a brief overview of the criteria assessed under these categories.

Other guidance on sustainability and steel building technologies is given in a recent SCI report [15] which includes many of the aspects identified in BREâ&#x20AC;&#x2122;s SmartLIFE report [16].

Table 14: Summary of other Code assessment criteria Category

Description

Water

Reduced indoor water use through more efficient fittings, appliances and recycling. Recycling of rainwater for external use.

Surface-water run-off

Management of surface-water run-off from developments. Minimising flood risk.

Waste

Storage of non-recyclable waste and recyclable household waste. Development of Site Waste Management Plans (SWMP). Provision of household waste composting facilities.

Pollution

Use of insulation with low global warming potential. Reduction in nitrous oxide emissions from space and hot water heating systems.

Health & well being

Provision of good daylighting. Provision of good acoustic insulation. Provision of outdoor space. Provision of homes that are accessible and adaptable to change.

Management

Provision of a home user guide. Good site practice through participation in the Considerate Constructors Scheme. Measurement and management of construction site impacts. Improved security by adopting Secured by Design principals.

Ecology

Encouragement of development on sites with low ecological value. Enhancement of ecological value of the site. Protection of existing ecological features. Promotion of efficient building footprints.

SmartLIFE project achieves productivity and site management benefits in March, Cambridgeshire

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P386 Code for Sustainable Homes: How to satisfy the code using steel technologies Discuss me ...

Code assessment for a medium-rise residential building A Code for Sustainable Homes assessment has been made of a medium-rise apartment built using light steel construction. For the Code issues that are directly relevant to the steel frame, i.e. energy and CO2 emissions and materials, the information already presented has been used in the assessment, i.e. SAP results and Green Guide ratings. For the remaining issues, conservative assumptions have been made on other cost effective measures that would sensibly be incorporated in Code Level 3 and 4 compliant buildings.

The relatively broad scope of the Code provides a range of design options to achieve the required number of points for compliance at each Code level. However, the mandatory requirements for energy and water, limit flexibility in these categories, particularly at higher code levels. Table 15 provides an explanation of the 34 Code issues and sets out realistic ways of achieving compliance with Code Levels 3 and 4 using steel framed construction.

For each issue within the Code, a short explanation of the scoring methodology is given and the points awarded are shown. In the right-hand columns, two indicative assessments have been made showing how many credits are assumed for each issue and what the equivalent points score is. These points are summed at the end of the table to show that the necessary minimum scores of 57 and 68 have been reached for compliance with Code Levels 3 and 4 respectively.

Table 15: Explanation of the Code issues with possible routes to Levels 3 and 4 compliance

Code Level 3 Issue

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