Title: Implications of Energy Performance Certificates on designing and managing office buildings
1Implications of Energy Performance Certificates
on designing and managing office buildings
- Tony Johnson
- Principal Consultant, Sustainable Energy
- BRE
2Content
- Statutory requirements
- EPBD
- CLG
- Display Energy Certificates
- Scope Basis of calculation A-G rating
- Advisory report
- Energy Performance Certificates
- Basis of calculation Reference values A-G
rating - Recommendations report
- Implications for design and management
- Measures Calculating benefit
3Statutory requirements
4EU Energy Performance of Buildings
Directive(EPBD)
- Requires Member States to introduce by end 2005
- Minimum Energy Performance Standards (New
buildings) - An acceptable methodology for calculating the
integrated energy performance of buildings - Minimum energy performance standards for new
buildings - Minimum energy performance requirements for large
existing buildings subject
to major renovation - Energy performance certificates (Existing
buildings) - Provided to prospective purchaser/tenant
- Prominent display of the energy certificate in
all public - buildings and institutions providing public
services - Regular inspection associated with
- Boilers
- Air-conditioning systems
- Calculations carried out in an independent
manner, by qualified and/or accredited experts
5CLG requirements -What is a building?
a roofed construction having walls, for which
energy is used to condition the indoor
climate a building may refer to the building as
a whole or parts thereof that have been designed
or altered to be used separately
6CLG requirements Building Regulations Part L
- To implement EPBD Articles 3 6
- Move to a whole building approach based on carbon
targets - Minimum performance to be set using SAP or SBEM
- No longer reliant on the elemental approach
- More attention to be paid to summer performance
- Stronger encouragement for Low and Zero Carbon
systems - Extends coverage of measures installed in
existing buildings - Firmer requirements for pre-completion testing
and log books - More self certification
- Came into force 6 April 2006
7Structure of Part L
- ADL1A new dwellings
- ADL1B work in existing dwellings
- ADL2A new buildings that are not dwellings
- ADL2B work in existing buildings that are not
dwellings
8CLG requirements EPCs, DECs and Inspections
- Provide EPC on construction, sale or rent
- Also recommended at design stage
- Must show asset rating
- ie numerical indicator of energy performance of
building fabric and services associated with
standardised use of building - Expressed on A-G scale
- Must not be more than ten years old
- Only few exceptions
- Places of worship temporary buildings (2 yrs or
less) less than 50sqm - Provide recommendations for improvement
- Display energy certificates for public buildings
- ie comparison of metered energy consumption with
benchmarks - Inspection of air conditioning systems
- boilers covered by other advice (Information
campaign)
9CLG requirements timescale
- EPCs are required on sale or let for
- New buildings - 6 April 2008
- Existing buildings depend on building size
- gt10000 m2 - 6 April 2008
- gt2500 m2 - 1 July 2008
- gt50 m2 - 1 October 2008
- Not required for property coming onto market
before size deadline, but will be needed by 1
October 2008 - Display Energy Certificates required annually for
all public buildings gt1000m2 from 1 October 2008 - Air conditioning system inspections required for
new systems within 5 years Existing systems
gt250kW by 4 January 2009, gt12kW by 4 January 2011
10Which certificate when?
- At the point of construction, sale or rent
- Dwellings and (almost) all other buildings
- Asset Rating - Energy Performance Certificate
(EPC) - Which building should I occupy?
- Compare assets on a consistent basis
- Calculation on a standardised basis
- How might that building be improved?
- Public display
- Initially large public buildings visited by the
public - Operational Rating - Display Energy Certificate
(DEC) - How good is this building and how well is it
being operated? - How can it be improved?
- Management and operation / Fabric and plant
11Inspection of boilers and air conditioning
- Air conditioning systems
- Inspection and report necessary
- Valid for max 5 years
- All systems gt 12 kW output
- Initiated by relevant person who has control of
system operation - Can be done in-house provided individuals have
appropriate training and accreditation - Content based on CIBSE TM44
- Boilers
- England Wales taking advice option
- Deemed to be provided by recommendations attached
to EPC and DEC - So no army of inspectors!
12Operational Rating Display Energy Certificate
13Operational Ratings - non domestic, public
buildings
- Based on measured in-use consumption data
- Includes intrinsic performance, plus effect of
- Actual plant performance
- Actual occupancy, location, etc
- Actual management practices by occupants at the
time - A comparative rating with respect to benchmarks
- Some normalisation for weather and occupancy
- Used to establish scope for improvement
- Must recommend improvement measures
- No theoretical calculation required
14DEC Scope
- SI 991 Reg. 16 (1)
- Applies to buildings with a total useful floor
area over 1,000m2 - occupied by public authorities
- and by institutions providing public services to
a large number of persons - and therefore frequently visited by those
persons.
15Central Information Point (CIP)
- Software specification
- Operational Rating / DEC information
- Postcode to Weather Region
- Monthly degree days
- CO2 intensities of fuels (kgCO2/kWh)
- Approved Benchmark Information
- Building types and benchmark categories
- Electrical and non-electrical energy densities
(kWh/m2/yr) - Separable use options
- Standard degree days
- Adjustment factors
- Approved template for DEC
16DEC Basis of calculation
- Operational Rating (metered CO2 / TUFA ) x 100
- (benchmark CO2 / m2)
- 95 of fuels must be metered
- Align DEC assessment period with Main Heating
Fuel - Synchronise other fuels measuring period
- Corrections allowed for metered
- Allowed separable energy uses
- Low and zero carbon inputs
- Exports
17DEC Basis of calculation
- Operational Rating (metered CO2 / TUFA ) x 100
- (benchmark CO2 / m2)
- Benchmarks are obtained from Central Information
Point (CIP) - based on CIBSE benchmarks - Converted to CO2
- Corrected for heating degree days
- Corrected for occupancy
- Where building has multiple activities and
metering only available at whole building level,
use area weighted benchmark
18DEC bands
Typical lower limit of D
- Failure to provide adequate information gives
default OR 200 ie G worse rating
19DEC data entry
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21DEC design
- A-G rating
- Current
- Carbon emissions
- Current
- Previous
- Operational rating
- Current
- Previous
- Administrative information
22Full Technical Table
- Annual energy use, CO2 emissions Units for
- and performance indicators Fuel and
heat Electricity energy data CO2 emissions Units
for CO2 data - Total energy use in the year concerned 100,000 230
,000 kWh 146.5 tonnes CO2 - Separable energy use deducted 1 (if
any) 5,000 150,000 kWh 83.5 tonnes CO2 - Separable energy use deducted 2 (if
any) 0 0 kWh 0 tonnes CO2 - Calculated performance indicators 95 80 kWh/m2
pa 63 kg CO2/m2 pa - Reference performance benchmarks
corrected 160 100 kWh/m2 pa 87 kg CO2/m2 pa - Benchmark ratios and Operational
Rating 59 80 Typical 100 72 Typical 100 - Operational Rating grade (A is best) Not
applicable Not applicable Not applicable C A to G - Units for age kWh
- Displaced energy Fuel and heat Electricity energy
data displaced Units - Fossil Fuel Energy Displaced 5,000 kWh 5 of
total - Grid Electrical Energy Displaced 16,000 kWh 7
of total -
- Building types Area (m2)
- Office 1050
- Benchmark category 2
- Benchmark category 3
- Benchmark category 4
23DEC Advisory report method
- Gather information from
- Building walk-around Previous knowledge
- Competent third party Existing valid reports
- eg EPC RR, AC inspection, LCC, etc.
- Software includes standard measures database
- Series of questions filter out irrelevant
measures - Assessor provides final check inputs own
measures
24DEC Advisory report contents
- Measures to improve building energy efficiency
- Short-term payback (0-3yrs)
- eg energy management
- Medium-term payback (3-7yrs)
- eg upgrading services
- Long-term payback (gt7yrs)
- eg LZC technologies
- Advisory report for information only.
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27Sample Advisory Report
28Asset Rating Energy Performance Certificate
29Asset Rating for EPC
- The calculated intrinsic performance of the
building as built - Normalised to standard conditions (weather,
occupancy) - Recognises different activities (temperatures,
occupation times) - Applicable to both new and existing buildings
- Automatically compares with a Reference
Building as the baseline - Generates a comparative rating (A-G and numeric
ratio) - Allows comparison between similar buildings on
level playing field - Compatible with compliance checking before
building is built - Produces recommendations for improvement
30EPC Basis of calculation
31Basis of calculation
- National Calculation methodology (NCM)
- ie SBEM or approved alternative software
- Looks at heating/cooling needs of every zone,
then system needs via efficiency hot water and
lighting similar - a lot of input data! - Standardised use rather than actual operating
pattern - To allow buildings with different actual usage
patterns to be compared - Comparison with a number of different buildings
- Notional (2002), Reference (2002), Typical of
existing stock (1995) - Improvement factors to upgrade to current
standards - When regulations change, improvement factors will
be updated - Being based on comparison reduces impact of
- survey error, modelling assumptions (zoning etc)
32Basis of calculation
- Notional building
- Same size and shape as actual building (but
glazing area depends on activity) - 2002 insulation standards
- Same HVAC strategy but with 2002 system type
- Each space contains same activity (and therefore
activity schedules including set point
temperatures and other parameters) as actual
space - Same orientation and weather
- Detailed definitions given in NCM Modelling Guide
(to be published soon) - Improvement factor to bring up to current
standards (2006) - Depends on HVAC strategy (ie greater improvement
for mech vent or cooled) - Low/zero carbon benchmark
- Notional with improvements Target Emission Rate
(TER) - Newly built benchmark
33Basis of calculation
- Reference building is same as notional building
but with - Gas heating
- Seasonal mixed mode cooling when temperature
exceeds 27oC - Cooling only counted when needed to avoid
overheating - Same regardless of HVAC system in actual building
- Improvement factor to bring up to current
standards (2006) - Same regardless of HVAC strategy
- Includes Low/zero carbon benchmark
- Reference with improvement Standard Emission
Rate (SER)
34Basis of calculation
- Typical building is same as notional building but
with - 1995 standard insulation etc
- 1995 standard HVAC systems
- Gives Typical of existing stock benchmark
- Actual building carbon
- calculated with the same calculation engine
- Generates the Building Emission Rate (BER)
35Basis of calculation
- Comparison with Reference Building improved by
fixed factor (23.5) - ie Standard Emission
Rate - Rating calculated as ratio BER/SER carbon x 50
- So 50 represents a building to current standards
- Converted into a rating band (A-G) but numerical
rating too - EPC includes reference values -
36Reference values
- Zero carbon
- Standard Emissions Rate
- Reference building with improvements
- Comparison with a new version of the same
building - If newly built
- Current Part L legal standard
- Compliant allowing for chosen HVAC strategy
- If typical of existing stock
- 1995 fabric and plant
- How good is this building relative to the stock?
37Reference values
- Zero carbon
- Top of band A
- Standard Emissions Rate
- B/C boundary
- Score 50
- If newly built
- Benchmark
- If typical of existing stock
- Benchmark
- D/E boundary
- Score 100
- Not necessarily typical
- To align with DEC
38Compare with DEC
39 40Recommendations Report
41Recommendations Report
- Offers suggested measures for improving the
intrinsic asset - Selected from a generic list of measures
- similar list as for DEC Advisory Report
- Filtered using
- Data input to calculation
- Results from calculation
- Additional information from assessor
- Then to be reviewed by assessor to subtract, add
or comment on measures
42Implications on design of offices - and
improvements
43Buildings can be more efficient
- New buildings should take Building Regulations as
a minimum standard - Not the target to aim at
- Better performance is perfectly possible and need
cost little or no more to build - Major refurbishment offers a golden opportunity
to improve performance too - The benefits are significant how can they be
achieved?
44The whole-system approach to design
- Site considerations
- Location and weather
- Microclimate
- Site layout
- Orientation
Integrating the design process Normally all
the really important mistakes are made on the
first day of the design process! - Amory Lovins
- Built form
- Shape
- Thermal response
- Insulation
- Windows/glazing
Daylighting strategy
Ventilation strategy
- Services strategy
- Plant and controls
- Fuels
- Metering
Source CIBSE Energy Efficiency in Buildings
Guide
45Where the savings come from
- Reducing demand for artificial heat, ventilation,
cooling and light - Orientation
- Layout
- Thermal responsiveness
- Daylight
- Natural ventilation
- Improve the efficiency of meeting that demand
- More efficient plant
- Optimum sizing
- Appropriate controls
46Design example - Daylighting
- Window design and building design has a direct
effect on - need for solar control and/or air conditioning
- size and capacity and space required for central
plant - air and water distribution system
- artificial lighting design
47Natural ventilation
- Three key issues
- building tightness (build tight - ventilate
right) - good ventilation for occupants
- natural ventilation design
48Natural ventilation example- The Environmental
Building, BRE
- Stop excessive solar gain through windows
- Minimise warming of the walls by the sun
- Minimise heat produced in the building
- Cooling by natural ventilation
- use of thermal mass
- night ventilation cooling
49But what about existing buildings?
50Implications of improvements using SBEM
- An existing 20 year old (anonymous) building
- Not bad, compared to typical
- What could be done with it?
51SBEM diagnostic options
52Example Output report
- Total consumption
- 236 kWh/m2/yr
- Heating dominates delivered energy
- Cooling and lighting could be improved to reduce
carbon emissions
53Example Recommendations Report
54Impact of selected measures
- Improve cooling efficiency
- New chiller
- Change life expired fan coils to chilled beams
- Improve heating efficiency
- New condensing boiler
- Optimum start, weather compensation and local
temperature controls - Improve insulation
- Double glazing
- Walls and roof
- Upgrade lighting controls
- Daylight sensing
- Occupancy sensors in meeting rooms and toilets
55Improved office
56New EPC
- Now C rating
- Closer to current standards
57Revised performance
- Total consumption reduced by 70kWh/m2
- Heating still dominates, but not as much
- Cooling reduced by 40
- Lighting reduced by 14
- Carbon down by 30
58Implications on management of offices
59Can you anticipate impact of improvements on DECs?
- You could implement advisory report measures on
the actual building - But what would be the change in consumption?
- DEC reflects actual measured performance
- Could estimate change and recalculate
- Eg use SBEM to estimate lighting energy
difference if better controls - But this would not be an official rating
- Proof of the pudding is in the metering
- Next time around!
60Summary
61So what are the benefits?
- New and refurbished buildings
- Raise standards across the board
- Level playing field for comparison - see what you
are getting - Avoid architectural greenwash - exaggerated
claims - Check on quality of buildings offered by PFI
contractors - Aligns with public opinion on mitigating climate
change - Low carbon is often more occupant-friendly
- Lower energy costs
62So what are the benefits?
- Existing buildings
- Asset rating allows comparison between buildings
offered to you on consistent basis - Manage portfolio - rent renegotiation, dispose of
poor buildings? - Operational rating checks whether buildings are
intrinsically poor or just badly managed - Proven environmental credentials help staff
retention - Proven environmental credentials help public
relations
63Remember
- Regulations and certification are not there as a
burden - they are vital drivers towards lower
carbon buildings through - Informing your decisions about choosing between
building options - Ensuring consistency
- Avoiding inadequate design and shoddy workmanship
- Helping you to get a building which is easier and
cheaper to run, with productive occupants - Potentially increased value
- Helping you to show all stakeholders that you
care about your buildings impact on the
environment - Everyone wins including the environment
64References
- Building Regulations and Approved documents
- http//www.planningportal.gov.uk/england/professio
nals/en/4000000000562.html - Questions on EPC rules interpretation - CLG
guide Improving the energy efficiency of our
buildings http//www.communities.gov.uk/publicati
ons/planningandbuilding/guidancenondwellings - Information on EPC, DEC Inspections
- Statutory Instrument http//www.opsi.gov.uk/si/s
i2007/uksi_20070991_en.pdf (as amended 1669,
3302, 647) - CLG Circular http//www.communities.gov.uk/publi
cations/planningandbuilding/circularenergy - SBEM User Guide Technical manual, NCM
databases - Go to http//www.ncm.bre.co.uk for download