Written evidence submitted by Tyndall Manchester (ENE0057)


 

 

 

 

 

Call for Evidence on Energy Efficiency

The Tyndall Centre for Climate Change Research is an internationally recognised climate-change research group, bringing together scientists, economists, engineers and social scientists to develop sustainable responses to climate change. Founded in 2000 as the first interdisciplinary research centre on climate change, Tyndall now includes five UK universities, together with Fudan University, China, who form the Tyndall Consortium, headquartered at the University of East Anglia.

This submission is by researchers at Tyndall Manchester based at the University of Manchester. All views within are attributed to the named authors and do not necessarily reflect those of researchers within the Tyndall Centre or the University of Manchester.

The research activity underpinning this submission has predominantly been funded by the UK Research Councils (EPSRC, ESRC and NERC) and references to further resources are provided where necessary.


Executive Summary and Key Recommendations

 

We agree that energy efficiency should be a national infrastructure priority. The timeframe for taking action to avoid dangerous climate change is extremely limited (Larkin, Kuriakose et al. 2018). Gaps already exist between existing national policies and what the Committee on Climate Change advises for the next two carbon budget periods (Committee on Climate Change 2018). The required substitution of heating and transport from fossil fuels to low carbon alternatives is greatly supported by improved efficiency throughout the energy system and therefore increased ambition on improved building energy performance is needed. This also presents an opportunity to reduce fuel poverty and improve health outcomes for vulnerable groups.

 

We also note however that if energy efficiency measures like the Energy Performance Certificate (EPC) are too narrowly focused on air tightness and heat loss there are risks of overheating health impacts and increased energy consumption for air conditioning demand; particularly when future climate projections are considered (Wood, Calverley et al. 2015). These risks vary by building location, both in terms of whether the area is urban or rural and regional disparities in climate across the UK. Ultimately issues of cooling and ventilation need to be embedded in considerations on fuel poverty also. A focus on reducing carbon emissions is a central priority of national infrastructure, but occupant comfort and affordability of cooling as well as heating are crucial. Furthermore, there is a need to better account for unregulated loads (equipment, catering, lifts) as well as for variations in building types, in EPC and other standards, especially in the non-domestic sector to ensure energy reductions are achieved in practice.

 

The evidence presented here gives insights into: the causes of the energy performance gap; the relationship between current energy efficiency strategy, projected climate change and overheating; neighbourhood through to regional variations in building performance; regional disparities in fuel poverty. These recommendations are based on insights from five ongoing research projects that are investigating: the impact of cooling and heating demand of hospitals on electricity grid as a result of climate change; understanding unregulated energy uses to accurately predict future consumption levels; the climate change impact on cooling demand of office buildings; the variation in spatial risk of overheating in buildings under future climates; mapping vulnerability to fuel poverty in the UK: Implications for future energy demand and sector governance.

 

The key recommendations we are making to the Committee are:

 

  1. Combining regulated loads (HVAC, hot water, lighting) with additional unregulated loads (equipment, catering, lifts) during the building design stage, and more comprehensive post-occupancy energy use evaluations helps to better replicate actual usage, and should be considered further for reducing performance gap issues.
  2. Ventilation and cooling (particularly passive forms) should be more fully considered in building energy performance assessments.
  3. Design for new and retrofit buildings should take into account regional climate and urban heat island effects in order to help avoid unintended overheating impacts when energy efficiency is improved. Due to these factors there are inherent risks of either overheating or increased air conditioning load if a ‘one-size-fits-all’ standard is applied.
  4. Use of the LIHC indicator to target fuel poor households who will be eligible for efficiency measures is likely to overlook certain households and regions that would benefit from upgrade.
  5. The BEIS fuel poverty metrics that will used to target the government's strategy to “upgrade the energy efficiency of fuel-poor homes” need to be expanded or adapted to encompass overheating, in additional to the current focus upon affordable warmth.


Energy Performance and the Performance Gap

 

  1. The energy performance gap represents the difference between the energy consumption predicted by building energy models and actual consumption in buildings. The performance gap exists for multiple reasons, such as extended occupancy hours and additional allocated equipment not considered during the design stage. Partially due to this performance gap, the energy performance of buildings is thoroughly variable, based on the different types of sectors.

 

  1. Literature on the energy performance gap suggests various causes for the mismatch between prediction and measurements. These causes can be grouped in three main categories: causes that pertain to the design stage, causes rooted in the construction stage (including handover), and causes that relate to the operational stage. The main reason for discrepancies between the modelling results and operational performance is the difference between the actual building operation and the assumptions used in the design (e.g. standard occupancy, fixed schedules of temperature set points, fixed airflow rates).

 

  1. Energy performance of buildings regulations have set out minimum levels of energy performance standards to be achieved by buildings, which are rated in their Energy Performance Certificates (EPCs) through simulation models. The performance standards are based on the benchmark of a set of existing buildings. However, research (e.g. Visscher, Meijer et al. (2016)) has shown that EPCs alone are insufficient at accurately portraying energy use of buildings and these comparisons between buildings do not drive and deliver the aimed decarbonisation targets. Benchmarks, when applied to energy performance in buildings, also act as a comparison method; this is where energy performance within one building can be compared to energy performance from a modelled simulation, or from a collective representation of other similar building types. Buildings in certain sectors occasionally compared through out-of-date benchmarks, such as the Chartered Institution of Building Services Engineers (CIBSE, 2012, citing data from 1996 for Higher Education buildings) and the National Calculation Methodology (NCM). Using a single set of comparative benchmarks is unadvised, due to the potential of out-of-date data and small sample sizes. So, energy performance across sectors, using the Higher Education Sector as the prime example, appears to be inadequately consistent. For a further example, out of 152 universities and colleges, HESA data (2017) suggests that between 2014-2015 and 2015-2016, only 70 universities managed to reduce their energy consumption per metre squared per annum (kWhm-2 per annum)  by over a unit of 10kWhm-2 per annum. This is a relatively low reduction in total energy consumption; comparing 2013-2014 and 2014-2015 data, the number of universities and colleges reducing by over 10Kwhm-2 per annum is just 32, thereby indicating certain universities and colleges are struggling to achieve consistent and significant annual energy consumption reductions. As a result, the Higher Education Sector has indicated smaller carbon reductions than initially predicted. It has been estimated that by 2020, universities will on average have reduced CO2 emissions by only 23% (Britegreen, 2016), compared to the 43% target set by HEFCE.

 

  1. Moreover, buildings’ operation may have in a near future an important role on providing more energy flexibility to balance the power network, and/or may also be integrated into more complex district energy networks with simultaneous cooling network flows, heating, and electricity. These systems may be fed by Combined Heat and Power, waste energy from industrial sources, included centralised or decentralised thermal and energy storage and aggregation of stock loads for demand response solutions. Therefore, energy policies on building stock need to be sustained by more complex system simulations and clearer optimisation objectives.

 

 

Recommendations

  1. Combining regulated loads (HVAC, hot water, lighting) with additional unregulated loads (equipment, catering, lifts) during the building design stage helps to better replicate actual usage, and should be considered further for reducing performance gap issues.
  2. More comprehensive post-occupancy energy use evaluations are required to better refine energy performance measures.
  3. The Government should liaise more with large organisations to uncover why energy performance gap issues are arising.
  4. Further financial implications for not reaching energy efficiency targets could also be implemented as for certain sectors there are few direct consequences.

 

 

Overheating

 

  1. Improved energy efficiency is recognised as a key factor in increasing buildings risk of overheating (Lomas and Porritt 2017). Overheating is the accumulation of warmth within a building to an extent where it causes discomfort to the occupants. Overheating causes a variety of health problems including, respiratory difficulties, heat and exhaustion, non-fatal heat stroke, and heat-related mortality. If building temperatures remain high during the night, residents’ sleep is affected, and this reduces comfort and productivity (Department for Communities and Local Government 2012). Though causes of overheating are complex – being a results of building fabric and characteristic, outdoor temperature, building use and internal gains – several recent studies of overheating suggest that higher energy efficiency from retrofit makes buildings more prone to overheating (Ibrahim and Pelsmakers 2018).
  2. There is no clear definition of the term ‘overheating’ or the specific conditions under which this can be said to occur. Nor is there any statutory maximum internal temperature in UK Building Regulations or current health and safety guidance. Overheating is not just a function of high temperature, other factors such as lack of air movement and sustained exposure to high temperatures will also affect the comfort level of occupants. A key issue the focus on air tightness and insulation for improved winter thermal performance, without sufficient ventilation and cooling can contribute to overheating. As such there are a number of different criteria of evaluation for overheating and standards and this has implications for building energy performance. The same building, following different criteria can pass on overheating assessment, but not on others. This then effects retrofit measures. For example Lomas, Giridharan et al. (2012) assessed overheating in a hospital building in future climates. Here two different criterion (HTM03 Criterion of 28 degrees celsius and BSEN15251 upper CAT 1 and CAT 11 thresholds) showed overheating was much worse particularly 2050s and 2080s when using BSEN criteria (see, for further reading on various overheating criteria see Zero Carbon Hub (2015).

 

  1. In addition low energy buildings such as zero carbon and passivhaus buildings have also been highlighted as a particular risk (Gupta and Gregg, 2018 Ibrahim, 2018). In some cases high energy efficiency buildings surpassing all overheating criteria under future climate projections by 2050s.When considering energy efficiency in the future these risks must be considered and careful incorporated into planning and design to ensure low carbon buildings not at risk of overheating.

 

  1. The UK Climate Impacts Programme gives projections that show even if global mean temperature rise is held at 2°C, there will be significant changes in UK temperatures trends (Wood, Calverley et al. 2015). By 2040 the temperatures experienced in the UK in the summer of 2003 (resulting in an estimated 2000 excess deaths in England) will be the norm (Public Health England 2015), and heat-related deaths could treble by the 2050s due to climate change (Zero Carbon Hub 2015). If overheating risks are primarily managed through air conditioning then this will have a significant impact on UK electricity demand by increasing summer loads (Wood, Calverley et al. 2015).

 

  1. If the pursuit of energy efficient buildings is too focused on reducing winter heating demand, as through the current EPC definition, interventions that lead primarily to much more airtight and highly insulated envelopes are likely to lead to more frequent occurrence of overheating or air conditioning electricity demand in buildings. Therefore several adverse consequences of driving building design based on singular optimisation problem (winter heating demand) are identified and ventilation and cooling aspects of building performance need greater consideration in setting energy efficiency measures.

 

Recommendations:

 

 

Spatial variation for overheating (urban heat island)

  1. One of the major factors influencing overheating is external temperature, which is itself influenced spatially specific factors. The Urban Heat Island causes large variations in temperature across cities. For example, a temperature difference of 9°C has been shown between parts of London and its surrounding rural areas (Kolokotroni and Giridharan 2008), this may have an impact on the risk to overheating for buildings, particularly their ability to cool down during the evenings. This can also vary by specific urban environment. The ability to open windows in order to ventilate a building is crucial in cooling down process. Many factors such as high levels of noise, high pollution from busy roads or high crime rates prevents windows from being open and particularly left open at night. Location in cities and proximity to busy roads should therefore be considered when increasing energy efficiency of a building, if ventilations from windows is a problem this should be taken in to consideration prior to retrofit or build. Similarly UK Climate Impact Programme climate projections show regions disparities in future warming, with London and the South of England likely to see much warmer summers than areas of the North of England and Scotland. Similarly energy efficiency policy and plans with should account for regional variations. Therefore the need to account for future overheating in relation to energy efficiency is most acute for urban areas in Southern England.

 

Recommendations:

 

Fuel Poverty

 

  1. Currently, fuel poverty is measured using a Low Income High Cost (LIHC) definition in England, and a 10% definition in Scotland, Northern Ireland and Wales. These definitions have limitations which may impact upon the success of efforts made by BEIS to target energy efficiency measures towards fuel poor households.

 

Regional disparities in fuel poverty

  1. The change from a 10% indicator to a LIHC indicator in England in 2012 as a result of the Hills Review has had implications for the type of households that are typically considered vulnerable to fuel poverty (Moore 2012).

 

  1. Analysis has shown that the change to a LIHC indicator has resulted in a national-scale shift in the type of household likely to be detected as fuel poor, from a 10% indicator that pinpoints fuel poverty amongst pensioner and off-the-grid households, towards an LIHC indicator that is more likely to recognise fuel poverty amongst low-income families (Robinson, Bouzarovski et al. 2018). There has also been a considerable reduction in the number of households recognised as fuel poor. In 2012, 13.79% of households were recognised as experiencing fuel poverty using the 10% indicator compared to 10.49% of households using the LIHC indicator (DECC 2015).

 

  1. This change has not been experienced uniformly across England (Figure 1). The difference in the percentage of fuel poor households between the two indicators is most substantial in the South West region where 7% fewer households are fuel poor using the LIHC indicator compared to the 10% indicator. Meanwhile, the North East and Yorkshire and The Humber have also experienced substantial reductions in fuel poor households, −6.1% and −6.4% respectively. The smallest reductions in fuel poor households are concentrated in London (−0.5%), the South East (−1.1%) and the West Midlands (−1.4%). This represents a transfer in relative fuel poverty towards these regions.

 

  1. The reduction in fuel poor households has concentrated in areas with lower housing costs, and there is subsequently a higher prevalence of fuel poverty in urban areas using the LIHC indicator. The condition is also more spatially heterogeneous, with fewer ‘hot-spots’ and ‘cold-spots’ of fuel poverty (Robinson, Bouzarovski et al. 2018).

 

  1. However, recent evidence also suggests that the LIHC indicator continues to overlook certain households who are likely to be fuel poor, as a result of the indicator design. This includes coastal communities with a high prevalence of disability and illness, an older population and entrenched income deprivation, and inner-city, urban areas typically comprise of a high number of privately renting and transient populations (Robinson et al. 2018). Many of these households would benefit from energy efficiency measures but are less likely to be classified as fuel poor using the definition adopted by BEIS.

 

Figure 1: Difference between the percentage of fuel poor households using the 10% and LIHC indicators for regions in England (Robinson, Bouzarovski et al. 2018)

 

Recommendations:

 

 

Incorporating cooling into the definition of fuel poverty

  1. Several groups are physiologically vulnerable to insufficient thermal comfort: older persons, young children, and those with a disability or illness. These groups are currently recognised in fuel poverty policy-making concerned with affordable warmth, but not in relation to cooling. Several other groups are also likely to be vulnerable to overheating. Residents of care homes tend to rely upon centralised heating systems resulting in a lack of individual control over thermal comfort (Brown and Walker 2013). The vulnerability of those living in the private rental sector to fuel poverty is increasingly recognised owing to a combination of energy efficient housing stock, a lack of housing rights and subsequent lack of control over energy efficiency improvements (Ambrose 2015). This is likely to extend to affordable coolth, especially in city regions. 

 

  1. Existing definitions of fuel poverty (the LIHC and 10% definitions) are concerned primarily with the issue of cold homes, despite acknowledging the need for other energy services such as lighting and cooking. For example, the most recent fuel poverty strategy for England “Cutting the cost of keeping warm” recognises that for “many low income households, actual expenditure on energy falls short of what is needed to provide adequate lighting, heating and appliance use”(DECC 2015 p.14). The issue of space cooling is not acknowledged anywhere in the strategy.

 

Recommendation:

 

 

 


References

Ambrose, A. R. (2015). "Improving energy efficiency in private rented housing: Why don't landlords act?" Indoor and Built Environment 24(7): 913-924.

Brown, S. and G. Walker (2013). Understanding heat wave vulnerability in nursing and residential homes. Comfort in a Lower Carbon Society Routledge: 65-74.

Committee on Climate Change (2018). An independent assessment of the UK’s Clean Growth Strategy – from ambition to action, Committee on Climate Change.

DECC (2015). Cutting the cost of keeping warm: A fuel poverty strategy for England D. f. E. a. C. Change. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/408644/cutting_the_cost_of_keeping_warm.pdf.

Department for Communities and Local Government (2012). Department for Communities and Local Government Annual Report and Accounts 2011-12 D. f. C. a. L. Government. London, The Stationary Office.

Ibrahim, A. and S. L. J. Pelsmakers (2018). "Low-energy housing retrofit in North England: Overheating risks and possible mitigation strategies." Building Services Engineering Research and Technology 39(2): 161-172.

Kolokotroni, M. and R. Giridharan (2008). "Urban heat island intensity in London: An investigation of the impact of physical characteristics on changes in outdoor air temperature during summer." Solar Energy 82(11): 986-998.

Larkin, A., J. Kuriakose, M. Sharmina and K. Anderson (2018). "What if negative emission technologies fail at scale? Implications of the Paris Agreement for big emitting nations." Climate Policy 18(6): 690-714.

Lomas, K., R. Giridharan, C. Short and A. Fair (2012). "Resilience of ‘Nightingale’ hospital wards in a changing climate." Building Services Engineering Research and Technology 33(1): 81-103.

Lomas, K. J. and S. M. Porritt (2017). "Overheating in buildings: lessons from research." Building Research & Information 45(1-2): 1-18.

Moore, R. (2012). "Definitions of fuel poverty: Implications for policy." Energy Policy 49: 19-26.

Public Health England (2015). Heatwave plan for England, protecting health and reducing harm from severe heat and heatwaves.

Robinson, C., S. Bouzarovski and S. Lindley (2018). "‘Getting the measure of fuel poverty’: The geography of fuel poverty indicators in England." Energy Research & Social Science 36: 79-93.

Robinson, C., S. Bouzarovski and S. Lindley (2018). "Underrepresenting neighbourhood vulnerabilities? The measurement of fuel poverty in England." Environment and Planning A: Economy and Space 50(5): 1109-1127.

Visscher, H., F. Meijer, D. Majcen and L. Itard (2016). "Improved governance for energy efficiency in housing." Building Research & Information 44(5-6): 552-561.

Wood, F., R.,, D. Calverley, S. Glynn, S. Mander, C. Walsh, J. Kuriakose, F. Hill and M. Roeder (2015). "The impacts of climate change on UK energy demand." Infrastructure Asset Management 2(3): 107-119.

Zero Carbon Hub (2015). Defining Overheating; Evidence Review. London Zero Carbon Hub

 

Submitted January 2019