Publication - Research and analysis

Energy Efficiency Standard for Social Housing: peer review

Published: 22 Oct 2013
Energy and Climate Change Directorate
Part of:
Environment and climate change

Peer review scrutinising the example dwellings in the Energy Efficiency Standard for Social Housing consultation document.

Energy Efficiency Standard for Social Housing: peer review
1 Executive Summary

1 Executive Summary

The key aim of this Peer Review is to scrutinise the Example Dwellings (formerly known as the "Case Studies") in the Energy Efficiency Standard for Social Housing ( EESSH) consultation document (issued June 2012), for the purpose of validation, and ensuring they provide clear, consistent and useful advice for social landlords regarding meeting an achievable standard. The setting of an EESSH is in line with the Scottish Government's climate change targets and the needs of tenants.

To do this, Heriot-Watt University considered the evidence base behind key assumptions underpinning the standard and the examples demonstrating how it could be met. Changeworks validated the modelling using the most up-to-date versions of the RdSAP software available. Changeworks also provided commentary based on retrofit work with housing associations and local authorities. David Adamson and Partners provided validation in relation to the costs of measures drawing on Quantity Surveying work for a wide range of social landlords. The report annex provides detailed commentary and validation for each of the examples used to inform the standard.

It is 23 years since the baseline for climate change targets was drawn up. In this era less data was collected than would be the case today. For instance the first Scottish House Condition Survey was carried out in 1991 and the methodology and coverage has expanded since then. Based on the available evidence, the baseline assumptions withstood scrutiny and were credible. However, it was noted that there could be alternate assumptions in terms of the baseline inputs for hot water tank insulation, loft insulation depth and in some cases, numbers of open chimneys. Alternative assumptions were assessed and are discussed both in the report and in further depth in The Report Annex: Review and Validation of Consultation Case Studies (now Example Dwellings) . When these variables were tested the results were not significant enough to invalidate the assumption used in the consultation. It was also noted that standards for loft insulation in the Scottish Housing Quality Standard ( SHQS) were less than building standards and, in most but not all cases, installers will have installed 200-250mm rather than the minimum 100mm currently required by SHQS. Overall, none of these issues would have an impact on the path to complying with either the SHQS by 2015 or EESSH by 2020.

The original selection of 23 retrofit example dwellings fitted well with the profile of the Scottish social housing stock, although there were areas ( e.g. flats) where coverage needed to be extended. These have been addressed through the provision of 12 further examples focused on harder-to-treat property types to illustrate strategies that show how the standard can be achieved. However, it must also be stressed that all examples within the EESSH are illustrative rather than prescriptive: landlords are free to meet the standard in whatever way they feel best meets the needs of their own stock and tenants. Aside from older tenements and modern system built housing with solid walls, it was reasonably practical to meet the standard without the need for 'advanced' measures. In the case of these harder-to-treat properties it is argued that external solid wall insulation should be classed as a 'further measure' applicable to the 2020 period, rather than an 'advanced measure' noted for meeting targets along the road to 2050. External wall insulation is an established technology and can attract funding from the Carbon Emission Reduction Obligation ( CERO).

Other notable observations were that:

  • Some communal measures are inadequately recognised by RdSAP; this could discourage landlords from implementing measures that are not always fully recognised as contributing towards the EESSH, but might still deliver benefits to tenants;
  • Certain improvement measures are likely to prove challenging to install across the board. A key example is external and internal solid wall insulation, where barriers may relate to planning restrictions, multi-tenure issues, tenant disruption, tenant refusal and/or insufficient subsidy to offset high capital costs;
  • Remodelling the consultation draft examples with a more up to date version of RdSAP (2009 v9.90) as opposed to RdSAP (2005 v9.83) resulted in a shift in the Energy Efficiency ( EE) and Environmental Impact ( EI) rating of a number of properties. This was almost entirely down to evolutions in the software and alterations to the base assumptions;
  • Utilising the expanded functionality in the latest version of RdSAP 2009 v9.91 such as specifying property specific rather than default U-values will boost the modelled baseline and post-improvement ratings of some properties but will have a converse impact elsewhere. It is recommended that the Scottish Government considers the evidence base that social landlords can draw on when deviating from the software defaults;
  • Off-gas properties may face greater challenges as they are likely to have lower energy efficiency and environmental impact ratings, reflecting the higher costs and carbon content of alternative fuels. The proposed standard anticipates this issue (with a lower standard for electrically heated properties) so any issues will be confined to particularly poorly performing properties that cannot achieve the desired energy efficiency rating via cost effective fabric improvements alone.
  • A new version of RdSAP was launched after the publication of the consultation document; the two versions were compared as part of this Peer Review and the enhanced facilities of the newer version tested. This established that a basic use of the newer version is unlikely to result in any significant changes over the previous version, and both have limitations that could affect the EE and/or EI ratings that some property types could achieve;
  • Upgrade measure costs were found to be broadly representative. Microgeneration system costs were queried, however these are subject to more change over time, particularly as funding changes and incentives are likely to play a part both in unit costs and uptake by landlords;
  • There is limited historic evidence showing the application of some improvement measures ( e.g. floor insulation) used in the retrofit examples;
  • Internal solid wall insulation presents major challenges to widespread uptake in the short to medium term. It should be noted as an 'advanced measure';
  • Additional costs to cover issues such as decants, staff negotiation time and specialist upgrade measures are likely to be an issue for some landlords;
  • Achieving both high EE and EI standards is likely to be difficult for some off-gas properties;
  • For certain microgeneration systems, landlords are likely to require investment of additional time and resources to ensure that tenants are able to use them effectively and realise the savings predicted;
  • The changing funding arena will inevitably influence landlords' investment decisions. While the impact of the Green Deal in social housing remains to be seen, the ECO and the pending domestic Renewable Heat Incentive ( RHI) are both likely to play a key role;
  • Legal issues, particularly those surrounding multi-tenure properties, will affect the ability of some landlords to upgrade their stock cost-effectively.

Whilst it was possible to cost the delivery up to 2020, the authors have some concerns about how accurate this calculation can be given the high number of uncertainties and assumptions that underpin it. As a starting point, the 35 retrofit examples dwellings offer a good profile but this can never really address the variations in the stock. This calculation is therefore provided as a guide rather than a definitive assessment. It is broadly in line with similar recent studies. The actual costs to social landlords will reflect prices at the time of installation and levels of support from mechanisms such as ECO.


Email: Agnes Meany