ENERGY USAGE IN OLDER BUILDINGS

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ENERGY USAGE IN OLDER BUILDINGS
Jon Wallsgrove Departmental Architect
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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
• Underlying unease about anti-conservation argument

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Age distribution of buildings - MoJ
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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

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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

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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.

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RESULTS
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Energy usage in courts by age
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Results
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• 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.

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ENERGY RELATED TO FUNCTION OVER TIME
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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

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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.

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CONCLUSIONS
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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

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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.

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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.

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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)

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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.

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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

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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.

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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

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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.

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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.