energy usage in older buildings l.
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ENERGY USAGE IN OLDER BUILDINGS. Jon Wallsgrove Departmental Architect. Background. Approx 800 buildings in HMCS portfolio Courts, office buildings, judges lodgings 20% listed buildings £60m annual energy bill for MoJ (HMCS, probation, prisons) 11.26bn kW/hr Age distribution

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energy usage in older buildings


Jon Wallsgrove

Departmental Architect

  • Approx 800 buildings in HMCS portfolio
  • Courts, office buildings, judges lodgings
  • 20% listed buildings
  • £60m annual energy bill for MoJ (HMCS, probation, prisons)
  • 11.26bn kW/hr
  • Age distribution
  • Underlying unease about anti-conservation argument
how the research was carried out
How the research was carried out
  • 33% of HMCS portfolio (256 buildings)
  • Broad cross section of property holding by size, type, age, location and usage.
  • Age split reflecting the overall portfolio
  • Data on variables
    • Size of building – sq.m.
    • Number of courtrooms
    • Function of building –court, office, residential
    • Type of court – Crown, Magistrates, County
    • Gas and electricity usage
    • Cost of energy used
    • Construction date
data analysis
Data Analysis
  • Sort by age
  • Energy /sq.m
  • Energy cost/sq.m
  • Energy/courtroom
  • Area /courtroom number
  • Energy/sq.m. by year
  • Energy/sq.m. by decade
  • Energy/sq.m. by construction history era
  • Energy/courtroom by construction history era
  • Energy/sq.m. by function
  • Area/courtroom by construction history era
data cleaning
Data cleaning
  • Anomalies and outliers due to erroneous data omitted from the analysis
  • Anomalies and outliers with significant affect on the results, as determined by sensitivity test, omitted from analysis
  • All buildings similar levels of staffing, IT usage, temperature, lighting levels, security etc.
  • All buildings regularly modernised, altered, and updated, so no age differential in quality of building or facilities provided.
  • Good and poor buildings in all age ranges.
The oldest buildings (pre 1900) use the lowest energy (216 kW/h per sq.m./ p.a.).

The pre-war buildings between 1900 and 1939 use 13% more energy (244 kW/h).

The immediately post war buildings (1940 to 1959) use 32% more energy (286 kW/h) and are by far the worst.

The buildings of the 1960s use 24% more energy (267 kW/h).

The buildings of the 1970s and 1980s use 11% more energy - similar to the pre-war buildings.

The buildings of the 1990s and 2000s equal the energy efficiency of the pre 1900 buildings.

efficiency of designs over time
  • - Pre 1900 most energy efficient (2574 kWh per court).
  • - The pre-war buildings increased by 44% (3709 kW/h per court) largely due to an increase in size of 18%.
  • - Post war buildings returned to the pre 1900 level (2625kW/h) due to a decrease in area of 3%.
  • - 1960s energy usage within 4% of pre1900, due to 19% reduction in area per court over the pre 1900.
  • - 1970s and 80s buildings increased their energy usage per court by 40%, due to a 19% increase in floor area.

- - 1990s and 2000s 68% more than the pre-1900 buildings, due to 42% increase in floor area per court

residential buildings
Residential buildings
  • The residential buildings (the judges’ lodgings) uses an average of 289 kWh/sq.m,
  • 25% more than the average for all buildings
  • 34% more than average for pre 1900 buildings
    • This tallies with other residential research.
  • This is probably due to the lodgings being in use for 24hrs a day rather than just for office hours.
  • Almost all the lodgings are pre-1900, so no statistically significant information on energy usage by age can be ascertained.
pre 1900 buildings
Pre 1900 buildings
  • the most energy efficient per sq.m. and per court.
  • the most efficient in use of space.
  • This is probably due to
    • high mass construction,
    • natural lighting,
    • natural ventilation enabled by high ceilings,
    • adaptable spaces
    • lack of mechanical air handling and cooling systems
    • users more tolerant of minor inconveniences due to higher quality of environment and greater personal space allowances.
  • These buildings are key assets to be retained
buildings between 1900 and 1939
Buildings between 1900 and 1939
  • as efficient in use of space and energy per sq.m. as buildings of the 1970s and 1980s.
  • There is large room for improvement.
buildings of the 1940s and 1950s
Buildings of the 1940s and 1950s
  • by far the worst group for energy efficiency
  • use 32% more energy but are only 5% of portfolio
  • doubtful whether the typical forms of construction used in this period can be economically upgraded to give acceptable energy efficiency.
buildings of the 1960s
Buildings of the 1960s
  • poor energy efficiency per sq.m., due to lightweight construction and poor insulation.
  • use 24% more energy but significantly are 25% of portfolio
  • energy usage per court is relatively good due to an exceptionally low average area per court (not clear whether this is because they are efficiently planned or because spaces are too small)
buildings of the 1970s and 1980s
Buildings of the 1970s and 1980s
  • poor energy efficiency per sq.m., probably due to internalised planning, lack of natural light and the use of air conditioning.
  • similar to pre-war buildings
  • area per court is fairly high giving a high energy usage per court.
  • worse in the 1980s buildings than in the 1970s buildings.
1990 to date
1990 to date
  • Almost managed to achieve the excellent energy efficiency per sq.m. of the pre-1900 buildings.
    • probably due to high insulation values, opening windows, natural lighting, assisted natural ventilation, efficient heating systems, sophisticated services control systems, the exploitation of passive solar gain and the use of solar shading.
  • Average energy per court is exceptionally high, caused by high average area per court.
    • increased areas for security at the entrance
    • the requirements of DDA throughout the building
    • improved witness facilities
overall conclusions
Overall conclusions
  • Energy usage in older public buildings does not follow the energy usage pattern of older residential buildings.
  • Pre 1900 and pre-war public buildings are more energy efficient than the latest energy conscious buildings, yet still have scope for further efficiency improvements.
recommendations 1
Recommendations 1
  • Buildings built pre 1900 should be prioritised for retention in the portfolio, with updated layout .
  • Energy improvements could be made to pre 1900 and pre-war buildings:
    • restoring opening windows,
    • reinstating natural lighting (e.g. rooflights),
    • restoring and assisting natural ventilation systems,
    • installing more efficient heating systems,
    • providing more sophisticated services control systems,
    • exploitation of passive solar gain,
    • use of solar shading - shutters, blinds and curtains
    • reinstatement of curtains for night-time insulation
recommendations 2
Recommendations 2
  • Buildings of the 1940s, 1950s and 1960s should be prioritised for disposal
  • In preference to renting space in buildings dating from between 1940 and 1990, redundant and underused space in pre-war and pre-1900 buildings (e.g. attics basements and outbuildings) should be refurbished and brought back into use for offices or courts.
recommendations 3
Recommendations 3
  • Since large new buildings are 42% larger than their 19th century equivalent, although refurbishment and new-build cost roughly the same per sq.m. at present , it would seem to be more cost effective to refurbish rather than replace large old facilities. This would avoid the 52% increase in energy usage.