UK Domestic Buildings Energy Efficiency

titles_energy efficiency_4

Written for the Coursera (MOOC) Class ‘Energy, the Environment and Our Future’ by Pennsylvania State University (March 2014).

In the UK there is concern over future electricity generation since most of the current Coal and Nuclear capacity is approaching end of design life.  No new Nuclear stations have been built since 1995 (Sizewell B), and of the nine in operation (9.2 GW) eight are due to be decommissioned within the next ten years.  Many of them have been extended beyond their design lives already.

Indigenous supplies of North Sea oil and gas is in decline.  The UK imports most of its oil from Norway, and much of its gas.

With ambitious targets set for emissions reductions of CO2, fossil fuel technology is being displaced by renewable energy sources.

Energy efficiency is becoming increasingly important in ensuring energy security.

Summary of Action for UK:

  • Continued and Improved National Investment in Building Insulation
  • Small short-term replacement of Nuclear Capacity
  • Continued development of Wind Energy
  • Continued Research and Development of Tidal and Geothermal Energy
  • Substantial Increase in Pumped Storage Capacity
  • National Focus on Decarbonising Transportation, R&D Investment

Building Insulation

A major component of energy consumption in the UK relates to losses from poor building insulation.  The UK housing stock is approximately 24.5 million homes.

TABLE_1_UK Energy Consumption

Domestic space heating in the UK accounts for 1/5 of total energy consumption. [1]

As a first step in energy conservation, these losses must be reduced by upgrading the thermal performance of sub-standard buildings.  Many buildings in the UK are hundreds of years old, 21% built before 1919.  Those other than new builds over the past decade are likely to have sub-standard insulation.

According to the Energy Saving Trust in an uninsulated home, 20% heat loss through windows & doors, 25% heat loss through the loft/roof space, 33% heat loss through uninsulated cavity walls  and 45% heat loss through uninsulated solid walls. [2]

The Green Deal (2012) is designed to reduce the upfront costs to the consumer of energy efficiency.  Repayment is made through savings on their energy bills.

The Energy Company Obligation (ECO 2013) places a duty on energy companies both to reduce emissions through undertaking solid wall insulation and to tackle fuel poverty by installing central heating systems, replacing boilers, and subsidising cavity wall and loft insulation.  [3]

Housing Stock

According to the English Housing Survey, Housing stock report 2008:

  • Around 22.2 million dwellings in England (26.3 in UK).
  • 15 million dwellings were owner occupied and 3.3 million were privately rented.
  • Remaining 3.9 million were fairly evenly divided between local authorities and housing associations.
  • One in five (21%) dwellings were built before 1919.
  • Three quarters of these older dwellings have been subject to at least some major alterations since they were built and 43% have had extensions or loft conversions added.
  • Dwellings built after 1990 accounted for just 12% of the stock.
  • The majority (81%) of dwellings were houses or bungalows; most of these being two storey houses.
  • Flats made up 19% of the stock.
  • The average useable floor area of dwellings in England was 91m2.
  • One in ten dwellings have attics (either as built and loft conversions).
  • 95% of dwellings were of traditional masonry or timber construction; the majority of these were cavity brick/block.

Although this only applies to England, it is a good approximation for the majority of UK housing. [4]

TABLE_2_UK Housing Stock

There is a housing shortage in the UK, and as the population is increasing, more homes need to be built.  There has been a steady increase in house numbers over the past six years, with new houses built with a good standard of insulation. [5]

TABLE_3_UK Home Insulation

As well as improvements in new housing, the existing housing stock is being improved, in both private dwellings and rented accommodation. [6]

TABLE_4_UK Domestic Energy Cons 2011

Heating in this relatively cold northern European country accounts for about 80% of domestic energy consumption, 60% on space heating alone. [7]

TABLE_5_UK Energy Cons 2011

Insulation in Older Housing Stock 

Houses with solid walls were commonly built before 1930 throughout UK.  They account for about 25% of the housing stock. [8]

This type of wall construction is the most difficult and expensive to insulate.  Whereas most cavity walled (double skin) buildings can be injected with insulation foam, solid wall have to be clad, either internally or externally.

According to the UK National Insulation Association:

The UK’s housing stock is estimated at approximately 24.5 million dwellings, of that approximately 36% consist of non-cavity wall construction – solid brick, solid stone, pre 1944 timber frame and non-traditional, i.e. concrete construction.’  [9]

 

Incentives to Upgrade

There are several incentive schemes on offer to property owners for insulation upgrade work, but the rate of improvement on the whole has been slow.

The UK Government Department of Energy and Climate Change realise that the two schemes on offer are not attracting enough participants. 

‘ Ed Davey (Energy Secretary) said that while take-up of green deal financing had been poor with just a few hundred homes using it, a million homes in England and Wales will have been insulated by April 2015 under the broader green deal scheme and its sister Energy Companies Obligation (ECO) since they began in January 2013.’ [10]

The ECO scheme is attributed as incentivising a large portion of the 457,000 properties insulated in recent years, still a small percentage of the tens of millions of homes with sub-standard insulation.

That scheme was implemented both to help insulate the homes of people in fuel poverty and difficult to insulate buildings, those older properties with solid walls.

The logistics and expense of having assessment reports carried out, and the unattractive 8% interest on finance are putting many people off.  The disruption of having modification work in your home is another disincentive.

Around 150,000 assessments (costing £100-£150), have been carried out since the Green Deal began, but the take-up of insulation work has been minimal. [10]

However, with energy prices rising, improved insulation is an obvious way to future proof against this.  Overall energy efficiency will help the country in reducing total energy consumption.

Analysis

CHART_1_UK Home Insulation Levels 1990-2012

The level of insulation varies with the age of buildings and the building standards at the time of construction.  It has only been since the energy crises of the 1970s that standards have improved.  Again the building standards were raised in the past decade in light of concerns over CO2 emissions and rising energy costs.

CHART_2_UK Average Heat Loss 1990-2012

Translating insulation quality into energy losses, the largest gains are by insulating very old buildings which have little or no insulation.  It is these buildings which are more likely to be solid wall.

The vast majority of buildings have some level of insulation, but would benefit from upgrading.  The spikes in heat loss 1991, 1993, 1996, 2010 and 2012, relate to low annual average temperatures.  More energy is required to maintain rooms at a comfortable temperature.  Leaky buildings lose heat at a greater rate.

CHART_3_UK Domestic Space Heating 1990-2012

The overall trend in space heating energy consumption is linked to the number of households, the average temperature and the quality of building insulation.

TABLE_6_UK Levels of Home Insulation

For the purposes of this analysis, I chose three levels of insulation, high, medium & low.  These relate to the building standards of the time.  The largest band of medium insulation level is a broad average which best fits the energy consumption data.

CHART_4_UK Energy Savings for Insulation

In 2012 it is estimated that 17.5% of the housing stock is well insulated.  This leaves a lot of room for improvement.  As can be seen, from the linear relationship between percent of homes well insulated to national energy savings, significant energy savings can be achieved.

References:

[1]  Digest of UK Energy Statistics 2012, UK Government (DECC)         

[2]  National Insulation Association, ‘Did You Know – Facts’, March 2014. 

[3]  The Carbon Plan: Delivering our low carbon future’, UK Gov 2011 

[4]  ‘English Housing Survey, Housing stock report 2008’, October 2010

(UK Department for Communities and Local Government) 

[5]  ‘Live tables on dwelling stock’, UK Gov – Dept Communities & Local Gov (Feb 2014) 

[6]  ‘Estimates of home insulation levels in Great Britain.’, UK Gov (DECC) Sept 2013 

[7]  ‘Special Feature – Estimates of Heat Use in the UK’, UK Gov – DECC July 2012

[8]  ‘How can I insulate my house if I don’t have cavity walls?‘, The Telegraph, 14 January 2014.

[9]  National Insulation Association (UK) 7 Mar 2014.

[10]  ‘Green deal loan take-up is ‘disappointing’, The Guardian, 5 March 2014

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