2015 Case study - Explanation
How to use the Case Study
1. Explanation of terms
• Occupants: Adults: 16+, Children: 0-15
• Construction: Age, house type and structural materials
• Key Features: A unique description of the home
2. The Measures Table
This table details the principal energy efficiency and renewable energy measures in the home. All information within the first four columns of the Measures Table was provided by the householder. The table details the following information:
• Measures Installed: The type of measure
• Product: The system or product used
• Disruption: This column details how disruptive the measure was to install, as rated by the homeowner. * – Low, ** – Medium, *** – High
• Cost: Financial cost of installing the measures at the time, with additional notes provided if necessary
• Potential Benefits: These are typical benefits, either non-numerical and generic to the measure or if numeric, according to the house characteristics, including type, fuel used, construction and size (not the individual home). Earlier case studies from 2015 use numeric data based on work by Sustain (www.sustain.co.uk) who are based in Bristol. The savings shown are representative of average carbon savings from a range of typical properties in Britain. Each house type has been modelled using BRE accredited RdSAP 9.91 software to calculate the baseline carbon emissions and the potential carbon reduction if the measure was installed. Each measure was modelled individually and therefore the carbon reduction potential of installing multiple measures may differ to results suggested. Note: the RdSAP methodology does not include an occupancy assessment, therefore actual carbon reduction may be higher or lower according to the occupant behaviour and interaction with the measures in the home.
2. The Measures Table
• The home: This section objectively describes the physical features of the home
• The story: A subjective discussion of the homeowner’s journey; this section explains their motivation, feelings, and reflection of their retrofitting process.
4. How this house performs
2019 Case Study Energy Usage Graphics:
This chart shows the household’s annual energy consumption and generation data compared to Ofgem’s Typical Domestic Consumption Values - industry standard values for the annual gas and electricity usage of a typical domestic consumer.(https://www.ofgem.gov.uk/gas/retail-market/monitoring-data-and-statistic...)
4. How this house performs
2015 Case Study Energy Usage Graphics:
These graphics are based on consumption data supplied by the householder compared to Bristol averages taken from the Government’s Statistical data set for Middle Layer Super Output Area (MLSOA) electricity and gas: 2011 (www.gov.uk/government/statistical-data-sets/mlsoa-electricity-and-gas-2011). Note: The 12 month energy consumption data supplied by the householder may not be taken over the latest 12 month period.
• Annual Electricity Use: The darker square represents the householder’s annual electricity use from the grid against the annual average electricity use for the average Bristol home. If the house generates its own electricity this has been factored into this usage and therefore represents grid electricity use.
• Annual Gas Use: The darker square represents the householder’s annual gas use. This consumption is compared against the annual average gas use for the average Bristol home.
• Carbon Per Person: Each home accumulates carbon emissions from their energy consumption in the home. Using the consumption data, we were able to calculate the number of tonnes of carbon each occupant in the house accumulates per year. Note; the total tonnes of carbon emissions for the home are divided by the number of occupants in the home, with children (under 16) counting as half an occupant, as used in some UK proposals for Tradable Energy Quotas (TEQs). Homeowner’s connected to a renewable energy supplier are assumed to accumulate zero carbon emissions from this consumption. Those using traditional grid energy suppliers have been given a carbon factor for this usage. The one for all domestic gas, 0.22674 kgC02e/kWh, is a 2012 figure provided by DECC and Defra (2012). The figures used for domestic electricity are based on emissions per supplier (http://electricityinfo.org/suppliers.php), which takes into account the fuel mix of each supplier, providing carbon factors of between 0 kgC02e/kWh for Good Energy and Co-operative Energy to 0.58 kgC02e/kWh for Scottish Power. The UK average is 0.43 kgC02e/kWh.
• Potential House type Energy Saving from 3 key measures: The data provided by Sustain was used to represent the average potential monetary savings for a house with the same characteristics (house type, fuel type, construction and size) as the case study house. The savings were combined for three key energy efficiency measures: loft insulation; external or cavity wall insulation; and floor insulation. These savings are represented by the difference between the darker square and the Bristol average fuel bills.
This text attempts to identify KEY factors that influence the figures displayed in the graphics above for ‘How this house performs’.
6. Energy Efficiency Rating
The Energy Efficiency Rating is included in producing an Energy Performance Certificate (EPC) survey which were conducted by The Positive Choice (www.thepositivechoice.co.uk). Note the Energy Efficiency Rating may not have been conducted post completion of the retrofitting process.
DECC/Defra 2012, www.gov.uk/government/uploads/system/uploads/attachment_data/file/69554/..., p.10
Sustain created and provided house type specific savings data for 2015 Bristol Green Doors case studies to increase the awareness of energy efficiency in the South West, in the hope that homeowners and occupants will be more willing to learn about the potential benefits of energy efficiency measures. Sustain support and commend Bristol Green Doors on the awareness that they are creating in the South West and look forward to supporting them further in the future. For more details on the work of Sustain go to their website: www.sustain.co.uk