Implementing Energy PerformanceCalculations

Dr Christine Pout

30th June 2003

Background

� FBE project last year exploring how simplified energysimulation tools could be used for the EPD

� Follow on research project which aims to develop a prototypedemonstration energy calculation tool –� Focus on the inputs and outputs

� Input data requirements/availability

� Uses of energy performance information

Overview

� Directive requirements and aims

� Defining energy performance

� Essential and desirable features of an energyperformance calculation methodology

� Information needed to determine energy performance

� The process of calculating energy performance

� Standardized occupancy, benchmarks and minimumstandards

� Provision of advice of EE improvements

Requirement and Aim of the Directive

� Requirement of the Directive – Measure the energyperformance, suggest improvements, extend minimumstandards to existing buildings.

� Aim of the Directive – Save Carbon

� Routes for meeting the aims of the Directive� Directing potential occupiers to choose/specify lower carbon buildings� Encouraging owners/managers to reduce a building’s carbon

emissions� Setting minimum standards to eliminate worst energy performers

� The Directive is an enabling step to achieve carbon saving

Defining Energy Performance

� The predicted energy performance

� For a standard level of service demand and occupancy– (theintrinsic energy performance)

� For a standard level of service demand and the actual occupancy

� For the actual level of service demand and the actual occupancy

� The actual energy performance

Presenting Energy Performance

� Energy Consumption (Delivered or Primary) and/orCO2 emissions

� per building / per unit floor area

� Normalised – for what?

� for external wall area/building shape

� region/external conditions

Essential/Desirable Features

� Minimize data input requirements/work with available data

� Consistency of results – repeatability

� Single procedure to cover� all relevant building types

� new and existing buildings

� Capable of showing compliance with minimum energystandards

� Provide a basis for energy efficiency advice

Factors Affecting Energy Performance

� Performance of the building envelope, e.g., thermalcharacteristics, Air infiltration rate

� Efficiency of heating, cooling, ventilation and lighting systems

� External conditions

� Service level requirements e.g., Internal temperature range,lighting levels and occupied hours

� Internal gains

� Building Operation Strategies

Energy Performance Calculation Process

Calculation Engine

Occupancy Details (temp, internal gains, hours)

Fabric Details

Regional Weather Data

System Performance

Energy Peformance Rating

Predicted EnergyConsumption

Data Required - energy performance

� New build - plans/design data� U-values of fabric elements, orientation etc.

� Heating, cooling, ventilation and lighting system types specified

� Installed capacity and efficiency of equipment

� Existing building - site survey� Observations of the building materials and envelope characteristics

� Visual assessment of (probable) system type

� Installed capacity and efficiency of equipment (where accessible)

� Log Book requirement (Part L2) useful source

Data Inputs for new buildings

yes

no

Calculation Engine

Standard Occupancy details (temp, internal gains, hours)

Fabric Details

Regional Weather Data

System Performance

Predicted EnergyConsumption

Modelled Building Service Details (HeatingCooling Lighting)incl. controls data

Typical System Performance

Data Inputs for Existing Buildings

yes

no

Calculation Engine

Standard Occupancy details (temp, internal gains, hours)

Fabric Details

Regional Weather Data

System Performance

Predicted EnergyConsumptionActual System

performance data available

Typical System Performance data

Building Type/Age plusSurvey

Construction data available

Infer

Standardized Occupancy Patterns

� Need standardized occupancy to allow fair comparisonbetween buildings

� Need to define a number of fixed building types (based onfunctionality) - Could be constructed using an activity basedapproach� e.g., Office = 75% office space, 15% circulation space 5% washrooms

5% storage.

� Buildings could be rated for more than one building usecategory.

Comparing Energy Performance

� Standardized energy performance provides the bestway for a buyer/tenant to compare the likely energyperformance in use between buildings

� Comparing calculated energy performance based onactual occupancy with actual energy consumption isbetter for determining operational energy savings

Calculating Consumption based on ActualOccupancy

Calculation Engine

Standard Occupancy Details (temp, internalgains, hours)

Fabric Details

Regional Weather Data

System Performance

Predicted EnergyConsumptionStandard Occ

Actual Occupancy details (temp, internal gains, hours)

Predicted EnergyConsumption(Actual Occ)

Actual Energy Consumption

OperationalSavings Potential

Benchmarks

� Empirical benchmark – based on the range of actualperformance for a building type.

� Tailored benchmark – adjust empirical benchmark to yourspecific building operation e.g., longer operation hours etc.

Comparing Actual Consumption

Comparing Actual energy consumption with

� Empirical benchmarks - tells you how well you aredoing compared to others in your “broad” class

� Tailored Benchmarks – (which can account forparticular mix of activities, occupancy patterns andfabric) tells you where your performance is comparedto where it should be.

Meeting minimum standards

� Could set minimum energy performance values for eachbuilding type

� Could compare energy performance rating to that of anexemplar building

� Could compare energy performance to one meeting minimumstandards e.g., elemental method Part L2.

Provision of advice of EE improvements

� Could be entirely separate from energy performancecalculation� Based on detailed energy audit and expert advice

� Generic (Action Energy Material)

� However, most energy advice requires much of the sameinformation as the calculation of energy performance. Socould add a decision tree onto energy performance calculationprocedure

Providing Energy Efficiency Advice

Calculation Engine

Occupancy details (temp, internal gains, hours)

Fabric Details

Regional Weather Data

System Performance

Predicted EnergyConsumption

Tailored advice plus info on typcial savings/cost effectiveness

Decsion Tree

Integrated Energy Saving Advice

� Rather than relying on typical savings, could use theprocedure to calculate the savings achievable in a particularbuilding.

� Calibrating the calculation to the actual energy consumptionwould� ensure more accurate assessment of the energy savings� Allow achievable operational savings (as well as fabric and system

savings) to be accurately assessed.

� Using this route also enables the cost effectiveness of energysaving measures to be assessed

Providing Energy Efficiency Advice and CostEffectiveness Calculator

Calculation Engine

Occupancy Details (temp, internal gains, hours)

Fabric Details

Regional Weather Data

System Performance

Calculation Engine

Occupancy Details (temp, internal gains, hours)

Fabric Details

Regional Weather Data

System Performance

Original EnergyConsumption

Energy Consumption with EE measure

ApplyEnergy Savings Options

Adjust Input Values

Carbon and Cost Saving

Cost of EE Options

Cost Effectiveness