Energy Efficiency Analysis

One 'survey output' associated with NBA housing stock surveys - is energy data and energy efficiency analysis and reporting.

A housing stock survey, will entail the collection and input of a large amount of data that is relevant to a specific assessment of the energy efficiency of the stock. The energy efficiency assessment involves a comprehensive analysis of data (based on the Standard Assessment Procedure), designed to: determine the heat loss, indicative SAP, NHER & BEPI ratings and CO² emissions for all identifiable dwelling variants; identify alternative 'target levels' of heat loss; identify priority needs for upgrading the energy efficiency of the stock.

NBA Consortium is a full member of the National Energy Foundation and has fully qualified NHER Assessors on its staff, operating with Auto-Evaluator software designed specifically to cater for the specific needs of large housing stocks

Levels of Analysis

In order to establish a full SAP or NHER rating, a considerable amount of information and data is required, much of which is specific only to energy efficiency - derived from either a full Energy Survey of the property or from detailed architectural drawings and specifications. As such, an assessment that accounts for all data items is normally considered inappropriate for the assessment of an entire housing stock.

For this reason, the NHER scheme has identified a series of Levels of rating - the level referring to the extent of information that is used to calculate the ratings, and thus their accuracy: with Level-2 corresponding to the full NHER rating As background:-

	Level-0 is the simplest level of analysis. It requires a minimum number of data items on the property. This rating has a standard error of +10%.
	Level-0 (Enhanced): this requires additional information on floor areas, wall types and exact heating systems - for each dwelling. This allows for the calculation and some further analysis of improvement options and costs, and data can be provided for each dwelling, individually. This level of analysis is ideally suited to housing stock surveys where low level sampling and the objectives do not warrant more detailed information.
	Level-1: This requires reasonably detailed and comprehensive information on each property, including dimensional information and detailed information on the construction, insulation and heating systems. It limits the assessment to the predominant type of wall construction, roof type, etc. & delivers ratings with a standard error of +5%. This is the level of assessment commonly applied to comprehensive surveys of managed housing stocks
	Level-2: This is the full NHER/SAP rating and requires all energy relevant information on each property. It differs from 'Level-1' principally in requiring dimensions for the full mix of materials (e.g. more than one type of wall construction, etc.). This is the level of assessment generally applied to 'scheme specific' or new-build assessments and is, generally, inappropriate for 'whole stock' analysis

The EU Directive, EPCs and RDSAP

The EU Energy Performance of Buildings Directive requires property owners to produce and provide to prospective buyers or tenants an Energy Performance Certificate, whenever a property is put up for sale or rent. The Directive will impact on the social sector because it requires an energy certificate to be provided for a) rental transactions b) right to buy/acquire sales and c) stock transfers

The Federation of Authorised Energy Rating Organisations has developed Reduced Data SAP (RDSAP), a simplified SAP methodology that is used to calculate the energy ratings of existing buildings, as required by the European Directive. RDSAP uses systems similar to the above to deduce the data that is not collected in the survey

To provide Certificates for social housing tenants, social housing providers will need to collect data, sufficient to allow an RDSAP calculation to be undertaken

Outputs

Regardless of the 'level' of assessment, SAP ratings, CO² emissions, and other performance indicators are provided for each dwelling, individually, (and for the whole stock, collectively) and held as 'attributes' within the data provided to the Council

The analysis allows for the identification and costing of all recommended improvement measures designed to raise the energy performance of the stock. Improvements are included as costed and programmed items of work (on an address specific basis) within the data provided. The analysis and reporting clearly demonstrates the costs and effects (in terms of SAP, and savings in fuel, fuel costs, CO² emissions, etc.) of implementing the measures identified