Building Sustainability & Compliance

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1 November 2011 WELCOME TO THE STROMA OCDEA TECHNICAL BULLETIN! This bulletin has been produced as a response to the latest full SAP conventions release, to ensure that our assessors are fully informed and aware of the changes made to SAP assessments following their implementation on the 1 st November In addition, we have explored the correct method of assessment for thermal bridging in SAP 2009 as this has been highlighted as an area of uncertainty by many of our assessors. Finally, we have presented examples of common scenarios and questions which have caused confusion recently, to assist those who may encounter similar issues. In this edition: - CLG Approved ACD Schemes status update - Thermal Bridging how to quantify junctions correctly - The Latest Conventions new additions explained - Questions & Answers relevant topics discussed CLG Approved ACD Schemes ACD forum meetings have continued to take place over the past few months. We would like to take this opportunity to summarise the outcomes so that those concerned can be kept up to speed with the latest developments. The proposed implementation date for CLG approved ACD schemes has been moved back from the previously anticipated introduction deadline of October Questions have been raised by industry representatives in relation to the on site inspection element of the proposed ACD schemes, and as such discussions are continuing to establish how this aspect would be integrated into the proposal as a whole. Whilst the discussion process continues, building junctions can still be modelled to receive a benefit in the thermal bridging section of SAP calculations, assuming that this is done by a thermal modeller with suitable expertise and experience as stated in the Building Regulations Part L1A 2010 document. The options available through Appendix K of the SAP 2009 manual for thermal bridging; to use accredited psi values, default worst case psi values, or the global y value of 0.15, remain applicable until CLG approved ACD schemes are implemented. As further details arise we will continue to provide updates such that assessors and those with an interest in the subject can benefit from such a scheme upon its potential future introduction.

2 Thermal Bridging In SAP 2009 calculations, two options currently exist for entering information on thermal bridging into assessments: 1. A default y value of 0.15 can be used, avoiding the need to quantify thermal bridging completely (no additional entry is required after making this selection to quantify junction bridging heat loss) 2. A bespoke y value is calculated for each dwelling* using Table K1 of the SAP 2009 document. *a y value calculated for another dwelling can be used assuming the original dwelling is identical to the dwelling being assessed, except for in orientation. Table K1 SAP 2009 Document Whilst option 1. is undoubtedly the simplest entry to make, as would be expected this gives a worst case performance for thermal bridging and can make it very hard to achieve the necessary compliance in terms of DER / TER improvement for new build dwellings. As such, the majority of assessors are now looking at option 2. as the preferred method; despite this being more work intensive and time consuming. This route allows bridging losses to be quantified to a level of accuracy, and where best practice details are used a significant reward can be achieved for bridging heat loss in SAP assessments. The following aims to explain how to treat each of the details defined in Table K1 of the SAP 2009 document as considerable, such that assessors can confidently calculate a bespoke y value for a dwelling using option 2.

3 Thermal Bridging Calculation Diagrams NOTE: Junctions where the dormer meets the main structure are disregarded

4 Thermal Bridging Calculation Diagrams Balconies The conventions (Appendix 1.3) state that: In the case of a balcony where the balcony support does penetrate the wall insulation, use the default value from Table K1 for junction E2. This means a psi value of 1.00 W/mK is used with this particular detail if present in a dwelling. This supersedes the footnote * in table K1.

5 Thermal Bridging Calculation Diagrams Junctions between two roofs These are disregarded, and such no psi values or lengths need to be included in the SAP calculations for this type of detail. Parapet Roof Junctions If the wall passes over the edge of the roof, treat as a roof with a parapet (E15 Table K1) If the roof passes over the top of the wall, treat as a roof without a parapet (E14 Table K1) Split level arrangements

6 The Latest Conventions The latest set of SAP conventions, Version 3.0, were released on the 29 th September 2011 and came into force on the 1 st November All SAP assessors were ed with notification to this extent. The conventions document is also available to download at the bottom of the following web page within the conventions tab: Where the information provided in this edition of the conventions conflicts with past documentation, the guidance in the version 3.0 document overrides all previous convention versions, and also the SAP 2009 procedure manual. Any SAP assessments completed after the 1 st November 2011 will be subject to audit checks which include the latest guidance provided by the version 3.0 conventions document. New and Amended Conventions As part of the conventions release, several new items have been included, and amendments and alterations have also been made to existing items Gable Wall Area confirmation of when to include this in calculations based on the roof construction present Internal Elements confirmation of how to include internal elements in thermal mass calculations 2.06 Bay Windows clarification on the entry of areas and junction lengths for thermal bridging calculations Window Areas confirmation that windows must be entered individually or at least per elevation Wet Rooms clarification on the assessment of wet rooms for SAP 5.08 Thermal Bridging, additional junction types additional information provided for balconies, split level arrangements, and corridors in blocks of flats Thermal Bridging around openings confirmation of the lengths to measure when entering window and door surrounds in thermal bridging calculations The key changes are summarised below: 1.08 Flats v. Houses a definition is given to assist in the decision making process. This has implications beyond SAP in terms of the FEE value also for CSH assessments Database Version confirmation that the latest version of the product characteristic database must always be used at both design and as built stages The explanations on the follow pages aim to digest and offer further clarification on these changes and additions to help our assessors understand how to apply them SAP Software Version confirmation of when an assessor can use a version of SAP software other than the latest available (also 1.11) 2.03 Dwelling Volume confirmation of the approach to use when measuring this

7 The Latest Conventions Flats v. Houses SAP Convention 1.08 has set out a distinction between a flat and a house as follows: A house or bungalow has both a heat loss ground floor and an exposed roof. A dwelling without a heat loss floor cannot be a house and must be treated as a flat or maisonette. Generally a flat or maisonette does not have both a heat loss ground floor and a heat loss roof (although there are some exceptions such as a ground floor flat with an extension or when the footprint of a flatted development is stepped ) Whilst ensuring that the correct selection is made for a dwelling for EPC and reporting purposes is important, this is particularly key in terms of the Fabric Energy Efficiency (FEE) value which is calculated in FSAP This item confirms that previous versions of the FSAP software can be used for report production if the results obtained at design stage have altered due to convention change or similar when as built stage is eventually reached, but only where building control are consulted and are prepared to provide written confirmation as evidence of this acceptance. A copy of this confirmation is to be retained by the SAP assessor in anticipation of audit. To clarify, existing issue 1.05 of the conventions states that the EPC should always be produced using the latest software version. How to do this in FSAP 2009? Credits are awarded in the ENE 2 section of Code for Sustainable Homes (CSH) assessments, based on a dwellings achievement in terms of FEE. It is significantly easier to obtain credits in this section for end terraced / detached houses than flats / apartments, since an allowance is made in such dwellings for extra heat loss from both an external ground floor and roof, and as such this definition provides clear guidance enabling assessors to make the correct selection with confidence for each dwelling. SAP Software Versions SAP Conventions 1.10 and 1.11 offer help when determining which version of the FSAP software to use for dwellings at each stage and in various locations: England & Wales the latest conventions state: SAP calculations must always be done using the latest version of approved SAP software (for SAP 2005 or SAP 2009 as appropriate) at both asdesigned and as-built stages. The only exception is where the as-designed calculation was done using an earlier software version and building control allows the use of that version for the asbuilt calculation

8 The Latest Conventions The current version number is shown in the bottom left hand corner of the FSAP software: Version numbers can also be found on the reports produced at both design and as-built stage: Scotland the latest conventions state: New build SAP calculations produced in support of standard 6.1 (carbon dioxide emissions) should be carried out using the version of SAP current at the date the building warrant application is lodged. This as-designed calculation may continue to use the same version of the software for the duration of the warrant process, including any amendment to the original warrant. Where a newer version of SAP is available, use of this in respect of standard 6.1 is at the discretion of the applicant. For the issue of an EPC on completion of the dwelling, the version of SAP current at the date of completion must be used (see item 1.05) This confirms that once a dwelling is completed in Scotland, if a later version of FSAP software is current, the information from the original version must be transferred into this using the method shown previously in order to lodge the EPC. Dwelling Volume SAP Convention 2.03 confirms that the dwelling volume is measured internally between finished surfaces of elements bounding the dwelling. Spaces outside of the habitable space are not included, even if within the insulation line. Gable Wall Area SAP Convention 2.04 confirms that the gable wall area is ignored as heat loss wall area in a dwelling when the roof insulation is at ceiling level. On the other hand, if roof insulation is at rafter level and hence along the slope, the gable wall should be included for heat loss. Do however note that in the case of a mid-terrace dwelling with rafter level insulation, the gable wall is a party element and hence would not be included as an external heat loss element. The gable wall area also needs to be included for heat loss if a flat ceiling defines the dwelling volume, with sloping insulation at rafter level above. This accounts for the actual heat loss which would be present in the dwelling in this arrangement. Thermal Bridging additional junction types SAP Conventions 5.08 and 5.10 provide guidance on additional junction types which need to be considered in SAP calculations, and the correct method of measurement for opening junctions. Appendix 1 of the conventions offers a concise breakdown of how to treat these new types, and our feature on thermal bridging in the previous pages of this technical bulletin provides extra information on this subject.

9 Questions & Answers Question? Dear STROMA, we have on a particular site a block of apartments with a 15kWp PV system present, solely contributing to the communal areas with excess electricity fed back into the landlords supply. How is this scenario entered into a SAP calculation? ANSWER To enter the PV correctly, you need to apportion the kwp produced by the array to the flats present in the block. This should be divided based on the floor area of each flat as a proportion of the total floor area of flats in the block. At current, no distinction is made in SAP between supply from PV to dwellings and to landlords supply, and as such this scenario should be entered using the method above. Example: A 15kWp array fed into landlords supply on roof of a block of flats, the block contains: 5 x flat type A, each of floor area 50m2 5 x flat type B, each of floor area 100m2 To work out the contribution for SAP in each of flat types A and B do as follows: Step 1. Total floor area in block = (5 x 50) + (5 x 100) = 750m2 Step 2. Calculate Type A contribution (50m2 / 750m2) x 15kWp = 1.00 kwp per flat Step 3. Calculate Type B -(100m2 / 750m2) x 15kWp = 2.00 kwp per flat Model these in SAP as though each was a dwelling with an individual PV array fed directly into it s supply, using the PV input panel in the renewables tab in the FSAP software. available to select but no apparent difference between these in their description. Each does however affect the SAP calculation in a different way. Which model should I select and why? ANSWER This is a very common question, and one that has caused much confusion in the past. Described simply, the three different products available in the database for this particular system reflect the different heat emitters which could be used with the system in a dwelling. This heat pump product can be used with various different heat emitters (radiators, fan coil units, under floor heating, & warm air systems) and each of these has an effect on the products tested performance, hence the change in SAP results when each database option is trialed. As for which product to select, the choice with the emitter which matches that present in the dwelling should be chosen. The three products in the data file are different in the emitter type column (see image below), and the correct reference number can be found from the description in the PCDF Specification document (page 31 item 13), available on the link below: sap/pcdf_spec_05_rev5.pdf From this, the possible references translate to : Radiators - 1 Fan Coil units - 2 Under floor heating 3 Warm Air Systems - 4 Extract from database search in FSAP 2009: Question? Dear STROMA, after searching for a NIBE fighter 360 heat pump in the product characteristic database table in the FSAP software, I have noticed that there are three different models

10 Questions & Answers Questions? Dear STROMA, can you please advise the input method for a rapeseed oil communal boiler within the FSAP 2009 software. Emission and unit prices, etc, are all listed within the SAP 2009 manual in Table 12 but it is not clear which fuel option this relates to within the software. ANSWER This scenario would currently need to be entered as heat from boilers oil in FSAP You will undoubtedly find that this will not have a particularly beneficial effect in the SAP calculation due to the emissions associated with this choice, but without providing further information it is not possible to rule out that standard oil will be burned in this scenario and as such a worst case choice must be made in SAP. It may be argued that this is not a fair representation of rapeseed oil which is the intended fuel source, but should fuel prices fluctuate / the site be sold to another owner to name but two potential scenarios, it is very possible that an alternative fuel which emits more carbon may be used in a multi-fuel product. The key exception to this is systems which can ONLY burn rapeseed oil. In this case a fossil fuel alternative could not be used in the system regardless of changes to fuel cost, ownership, or other future outcome, and hence in this case the choice heat from boilers biogas can be selected as the closest description of the actual fuel used. The same is also true were biodiesel is the intended fuel source unless ONLY biodiesel can be burned by the system, the worst case oil option must be selected. Heating systems are now available in the market with integral nozzles which ensure that only certain fuels can be burned. If these are used, ensure that product evidence is collected by the SAP assessor along with client confirmation to prove this in anticipation of audit. Questions? Dear STROMA, I am just about to start my first extension job under the L1B regulations. This will fall under the 2010 regulations, so I am asking for some clarification on the process to follow. My assumption is that I should use FSAP 2009 to model the existing dwelling with a notional extension using limiting values to give me a target emission rate, and then separately model the existing dwelling with the actual extension including the details from the architect / clients specifications instead. I then need to demonstrate that an improvement is achieved by the actual model over the notional one. Is this correct? ANSWER This is indeed a very common way of proving compliance for extensions with elements of part L1B of the building regulations, but the first thing to do when working on extension projects is to contact the relevant building control body and ask what their requirements are. The majority of bodies will require this method, but some still allow area weighted U values and specifications to be provided without SAP calculations to obtain compliance. Assuming that the notional vs. actual comparison method is required; the existing dwelling should be modeled in FSAP using the most accurate information available (Appendix S data can be used in absence of this. A notional extension is included in the model of the same size, shape, and area* as the proposed extension. Each of the extension elements is then assigned a notional property (limiting value) from Table 2 of the Part L1B 2010 regulations, on page 17. (see following page) *Note that glazing should have an area equal to 25% of the extension floor area + area of any covered or removed openings in this notional model. Once all aspects are entered, a notional DER value is obtained, and can be evidenced through production of a DER worksheet.

11 Questions & Answers (cont d) Next, the existing dwelling is modelled again using the most accurate information available, but this time the actual extension is included in the model with the properties stipulated by the client / designer. The actual areas of windows are included, and the proposed thermal properties are assigned to each element of the extension. Upon completion an actual DER value is obtained, again evidenced through production of a DER worksheet. This can then be compared to the notional DER obtained in the previous step, with the objective being to ensure that the actual value is less or equal to the notional (in a similar way to obtaining a DER less than the TER for a new build dwelling) to prove compliance with this aspect. It is worth remembering that improvements to the existing dwelling are permitted to obtain an actual value less than the notional DER, but these should be included in the actual model only. Other items may also need to be provided to building control to prove compliance with L1B, which should be pointed out by them when consulted ahead of beginning these calculations.