the green deal tools -richard hartless, bre

Part of the BRE Trust

The Green Deal toolsRichard Hartless

CoRE Learning Event : 25th October 2012

Overview

1. What is Green Deal

2. Introduction to BREDEM and SAP

3. Developments to SAP

4. In-use factors

5. Occupancy assessment

6. Improvement measures and tool outputs

7. Non-domestic Green Deal [If time!]


How does Green Deal work?

How does the Green Deal work? Example: domestic owner occupier

4

Customer interest

Assessment QuoteAccept quote

Installation & after

Can happen at the same visit

impartial assessors

work out what households

need

Customers choose what work

they want done

Quotes are personal and

include subsidies

Installers

Costs charged to

electricity bill

Stays with home if move

Assessment

Customers will get an impartial on-site assessment of their home, from authorised Green Deal Assessor. Assessment is in two parts:

• Customers get an Energy Performance Certificate, which is based on standard assessment of how home is used

• Green Deal Assessor then has conversation with customer about how they actually use the home

• Assessor produces personalised “Occupancy Assessment” so customer can understand what improvements to the house are most appropriate

• Assessment is like prescription, it can be used with any business providing Green Deals

• “Golden Rule”: Green Deal aims to let householders save at least as much in energy costs as they repay through their electricity bill

Customer interest

Assessment

QuoteAccept quote

Installation & after


Introduction to SAP and BREDEM

BREDEM - BRE Domestic Energy Model

– BREDEM calculates annual energy required for:• space heating• water heating• cooking• lights and electric appliances

– From energy cost, carbon emissions

– First version in 1980s• subsequent continuous development and testing

– Extensively compared with energy consumption for both real houses and detailed simulation models

BREDEMschematicof principles

SAP also estimates: • Hot water energy• Lighting energy• Energy needed for

pumps and fans

But not appliances and cooking energy

The overall heat transfer coefficient, H (W/oC):

– Ai is the area of an external element (m2)

– Ui is the U-value of an external element (W/m2 oC)

– Ltbi is the length of a linear thermal bridge (m)

– i is the linear thermal transmittance (W/m oC)

– nT is the total air change rate (ach)

– V is the volume (m3)

Space heating energy use:– H (heat transfer coefficient)

– θe mean external temperature

– θi mean internal temperature

– Gi internal heat gains

– Gs solar heat gains

– gain utilisation factor

– e heating efficiency

Basic equations

e

GsGieiHspaceQ

)()(

BREDEM – comparison with real dwellings(176 dwelling years of data)

Space heating - All data (new)(monthly data compared with BREDEM 8 predictions)

y = 1.0022x

R2 = 0.8501

0

1000

2000

3000

4000

5000

6000

7000

0 1000 2000 3000 4000 5000 6000 7000

Measured (kWh)

Pre

dic

ted

(kW

h)

BREDEM – comparison with simulation models

MONTHLY PREDICTIONS OF EACH MODEL(SEMI-DETACHED, MODERN HEAVYWEIGHT)

0

200

400

600

800

1000

1200

1400

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Pre

dict

ion

(kW

h)

ESP

HTB2

SERI-RES

BREDEM 8

SAP - Standard Assessment Procedure

– SAP is a version of BREDEM with some fixed parameters

– Not affected by (fixed parameters)• number of occupants (assumed, based on floor area)• ownership of particular electrical appliances• heating patterns and temperatures• geographical location

(but in latest version parameters can be adjusted - Green Deal Occupancy Assessment)

– Depends on• thermal insulation• ventilation• lighting• dwelling energy generation (e.g. PV panels)• solar gain• heating system efficiency and controls• cost of fuels

SAP 2009 - Standard Assessment Procedure

UK Government’s energy rating method for dwellings. Space and water heating, ventilation and lighting, less energy generation.

– SAP rating• 1 to 100 based on annual cost (per m2)• Required for all new homes• Energy Performance Certificates (RdSAP) for existing homes• Widely used by social housing providers, encouraged by Govt.

– EI (Environmental Impact) rating• 1 to 100 based on annual CO2 emissions (per m2)• Energy Performance Certificates (RdSAP) for existing homes

– DER, Dwelling CO2 emission rate• CO2 emissions (per m2)• Must meet TER (Target Emission Rate) to comply Part L1A

Energy Performance Certificates [Old]

– Energy Performance Certificate provides:– An ‘energy’ efficiency rating for a house

(actually based on costs)– A CO2 based Environmental Impact rating– Recommendations for efficiency

improvements to the dwelling– All this is generated by SAP, following a

physical survey by a DEA

– EPCs required by law when dwellings are sold or let

– Green Deal will piggy-back on the EPC process


Developments to SAP

RdSAP

– RdSAP is not an alternative version of SAP

– It is an inference procedure for generating the full set of SAP inputs from a smaller set of data

– The inferred data is then run through a normal, full SAP calculation

– Devised when EPCs were introduced to make it easier for assessors (to keep costs down)

How SAP and BREDEM have changed over time

– Fundamentally, changes have been minor over the years (i.e. the same basic physics applies)

– But models now deal with many more systems and technologies than early versions – so lots of add-ons (consequently, there are now many appendices in the SAP specification)

– There was a fundamental change in SAP/BREDEM in 2009: monthly calculations

– This actually makes the calculation simpler in some respects: 12 simple calculations instead of 1 complicated one

Current developments

– SAP 2012 has introduced relatively minor changes:– Updated fuel costs and CO2 emission factors– Climate data extended to allow regional calculations in

some circumstances– Height above sea level temperature correction– More primary pipework options (e.g. partially insulated

now possible)– Proposed changes to be introduced in SAP 2012 have been

consulted upon. An initial analysis of the responses has been undertaken but more remains to be done (key areas of contention are on CO2 emission factors and heat pumps).

– Formation of a SAP Scientific Integrity Group to assist by making recommendations on more contentious issues

SAP developments for Green Deal

– Essentially a new hybrid of SAP and BREDEM

– Based on RdSAP inputs plus data from the Green Deal ‘Occupancy Assessment’:– EPC gives standard savings for improvement measures

(on which ‘Golden Rule’ is based)– Includes ‘in-use’ factors to reflect actual performance of

measures– Occupancy Assessment gives occupant-specific savings

• Low energy users won’t save as much, so we need to warn them!

• Unhappy finance providers• Undermine confidence in Green Deal

New EPC

- Revised presentation

- Refers to Green Deal

- Environmental Impact

relegated to page 4

- Potentially accompanied by GD ‘Occupancy Assessment’

- Will contrast standard savings for measures with occupant specific savings


In-use factors

These are some of the things you can have done to your property

•Cavity wall insulation•Cylinder thermostats•Draught proofing•Solid wall insulation•Condensing boilers•Heat pumps•Heating controls•Lighting systems•Biomass boilers•Cylinder thermostats•Draught proofing•Duct insulation•Hot water

showers/systems/taps

•Fan-assisted replacement storage heaters

•Flue gas heat recovery devices

•Heating, ventilation and air-conditioning controls

•Replacement and secondary glazing

•Under-floor heating•High performance external

doors•Hot water controls •Lighting systems, fittings

and controls•Mechanical ventilation with

heat recovery

•Pipe-work insulation •Microgeneration•Chillers•Condensing boilers•Replacement glazing•Roof insulation•Sealing improvements•Under-floor heating•Under-floor insulation•Variable speed drives for

fans and pumps•and more...!

If it is on this list then you would get it in part or whole through GD

http://www.decc.gov.uk/en/content/cms/tackling/green_deal/greendeal_guid/greendeal_guid.aspx

http://www.decc.gov.uk/en/content/cms/tackling/green_deal/greendeal_guid/greendeal_guid.aspx

In-use factors

• Bridge gap between theoretical and actual performance (difference between in-situ and laboratory, poor installation, comfort taking etc.)

• Provide additional consumer protectionWhat are they?

• Review of published evidence (e.g. NEED, Field trials etc.)

• Recommendations from DECC convened expert committee

How were they derived?

• % reduction factor applied to each measure in the Green Deal tool

How are they applied?

• Objective is to lower factors over time so will review evidence of performance every year

How will they be amended?

In-use factors Domestic Measures Sources of Evidence

In-use factor (%)

Cavity Wall Insulation Field trials and NEED 35 Internal Solid Wall Insulation (pre-1966 solid brick walls)

Field trials and NEED 33

Internal Solid Wall Insulation (all other solid walls) Recommendation 25 External Solid Wall Insulation (pre-1966 solid brick walls)


External Solid Wall Insulation (all other solid walls) Recommendation 25 Loft insulation (including loft hatch, rafter insulation)


Flat roof insulation Recommendation 15 Room in roof insulation Recommendation 25 Floor insulation Recommendation 15 Heating controls Field monitoring 50 Non condensing to condensing gas or oil boiler Field trials and NEED 25 Biomass boiler Recommendation 25 Biomass room heater Recommendation 25 Flue Gas heat recovery device Recommendation 10

Hot water cylinder insulation Recommendation 15

Double Glazing Recommendation 15 Secondary glazing Recommendation 15 High thermal performance external doors Recommendation 15 Draught-proofing Recommendation 15 Cylinder thermostat Recommendation 10 New or replacement storage heaters Recommendation 10

Replacement warm-air unit Recommendation 10

Waste water heat recovery devices Recommendation 10

Solar water heating Field trial 0 Photovoltaic panel Recommendation 0 Ground source heat pump Field trial 10

Air source heat pump Field trial 25 Micro CHP Recommendation 25 Building mounted wind turbine Field trial 0


Occupancy assessment

Occupancy assessment data

Number of occupants

Shower type, showers and baths per day

Heating system and heating in each room

Temperature in living room

Heating patterns

Appliances & cookers

Fuel tariffs and consumption together with reliability

How occupancy data is used

• Used to calculate hot water, appliance and cooking uses

• Affects space heating requirement to via gains

Number of occupants

• Used to calculate hot water use• Electric showers add to

appliance consumption• Affects space heating

requirement via gains

Shower type, shower

frequency, bath frequency


• If an alternative system has been chosen, heating efficiency, controls and responsiveness are adjusted accordingly

• Directly affects space heating energy requirement

Heating systems

• Used to estimate proportion of dwelling that is unheated

• Used to calculate average internal temperature

Heating in each room


• Used as starting point to calculate average internal temperature

Living room temperature

• Used to calculate average internal temperature to estimate how much dwelling cools down between heating periods

Heating pattern (times)


• Used to estimate tumble dryer energy consumption (together with number of occupants)

• Affects space heating consumption via gains

Proportion of drying done in tumble dryer

• Used to estimate cold appliance consumption• Affects space heating consumption via gains

Number of fridges and freezers

• Used to estimate energy required for cooking• Affects space heating energy via gains

Cooking type and fuel


• Used in place of SAP default values to obtain more accurate estimate of running costs

Fuel tariffs

• Where reliable, used to reconcile calculated energy consumption by each fuel with actual amount used

• Software scales all uses of that fuel up or down accordingly

Fuel consumption

data


Improvement measures

Improvement measures – standard savings

– Model is run with standard SAP occupancy assumptions

– Model is re-run with energy efficiency measures added (sequentially)

– The saving for each measure is calculated– The amount of Green Deal finance available for

each measure is based on this

Improvement measures – tailored savings

– Model is run using the occupant specific information

– Model is re-run with improvement measures added

– Savings for each measure are calculated– These are used to advise occupant on what they

are likely to save if they installed these measures– Warns them if this would mean they are unlikely to

‘pay for themselves’ even if they are eligible for GD finance

– But they can still go ahead if they want to

Occupancy Assessment report

– All this information (and more) is presented in the Occupancy Assessment report

Summary

– SAP is normally used with standard occupancy assumption so we can compare dwellings fairly

– For GD we need something specific to the occupants

– Occupancy information is collected and entered it into a modified version of SAP

– This estimates savings from improvement measures specific to household

– In-use factors are also applied

– Avoids overestimating savings and potentially undermining confidence in the scheme


Non-domestic Green Deal

The Green Deal for non-domestic properties

Scheme is broadly the same for both homes and non domestic buildings, and available at the same date.

Some variations:

•Assessment: non domestic buildings often have more varied characteristics than homes, so the assessment methodology will need to be more complex;

•Measures: for simplicity, a single comprehensive list of qualifying improvements for both homes and non domestic buildings.

•Calculation of Green Deal finance: more flexibility for the non domestic sector by allowing for specialist assessments to provide a more detailed savings estimate.

– Starts from the existing SBEM calculation tool, which uses standard conditions to calculate energy performance metrics and recommendations for improvement.

– Generate an EPC for the target building, along with the accompanying Recommendations Report.

Step 1

Step 2Tailoring

– Have reviewed which parameters within the Activities Database (operating hours, occupancy density, equipment loads, etc.) are most sensitive in terms of their effect on actual energy use and likely savings.

– Allow user to modify some or all of these parameters to create new Activities specific to the building

– One key element of tailoring is the level of energy management currently employed – links to normalisation

– Modified interface (iSBEM) to allow the assessor to amend the building model to incorporate one or more of the recommendations – and keep track of the effect

– Package measures in different scenarios

– Require the assessor to input a value for the marginal cost of each unit of each fuel as currently paid by the building occupier.

– Tool produces comparative tables of energy, carbon and costs savings for each scenario

– One scenario to be selected as proposed GD package – used to create Green Deal Report

Step 3Handling Recommended Measures

– Assessor is required to enter either the results of a DEC assessment (preferred), or actual meter readings for the previous year.

– Assessor needs to assess and enter a measure of how well (or otherwise) the building appears to be being managed, in different areas of operation (policy, HVAC, etc)

– With this information, the tool recalculates figures obtained above, normalised to match the actual management and usage of the building.

– It will also calculate the likely savings from improving management alone

Step 4Normalisation

Energy management

– Assessment is based on well-established Energy Management Matrices

– Assessor matches observed behaviour to a series of questions, to obtain a score

– Covers different topic areas

– Based on material developed under the Energy Efficiency Best Practice programme, then Carbon Trust – and a new BRE Trust Report

Results

– This version of the tool will provide the building owner and any potential GD provider with enough information to know – a) whether a GD solution could save energy and – b) which sort(s) of measure would be worth pursuing– c) the scale of likely savings

– Pilot version has been available for trial by key stakeholders since November 2011 at www.gdtool.bre.co.uk.

– Latest version (v5.0.b) released on 21st August 2012

– Final version scheduled for October

Current stagePublic trial versions

http://www.gdtool.bre.co.uk/


The Green Deal toolsRichard Hartless

CoRE Learning Event : 25th October 2012

the green deal tools -richard hartless, bre

Technology