FEATURE ENERGY MANAGEMENT SYSTEMS Mind the gap between design and use
Dr. Andy Lewry and Ms. Lorna Hamilton from the Building Research Establishment evaluate the difference in performance, between design and the building “in-use and how to address energy efficiency short-falls
issues – what was needed was a controlled study to investigate this; not attempting to link datasets;
Design was not an issue but operation and the associated issues seemed to be the cause, however there is only anecdotal evidence to support this. A study is needed to codify and quantify the causes of poor performance in use;
W
e have the ability to design good buildings and the knowledge to
operate them in an effective and efficient manner – so why doesn’t it happen? The construction industry has in general been “designing for compliance” using software with “standardised driving conditions”. We know how to build good performance buildings but the issue seems to be having the design feed through to performance-in-use. This has led to what has been termed the performance gap. In reality this has two components (see figure 1): The compliance gap; and Actual performance gap The overall gap has been estimated at
between 200-450% of which the modellers estimate 50-70% is the compliance gap and can be solved with more realistic modelling mirroring the conditions in operation more closely. However, the underpinning reasons for the second and larger actual performance gap are generally unknown. There is a lot of speculation and hypothesis but little investigation and hard evidence.
INVESTIGATING THE GAP BRE has previously attempted to close the gap by using the Green Deal Tool to map Energy Performance Certificates (EPCs) onto Meter readings; although this approach has merit the sliding energy management scale has little underpinning research to support the assumptions and no verification has been carried out to support these judgement calls by expert groups.
10 SUMMER 2017 | ENERGY MANAGEMENT Anecdotal evidence from the asset
management industry has indicated a number of possible reasons: Issues with the management structure and governance; Lack of maintenance due to resource and skills shortage; Limited data; Lack of practical solutions and their costs However, the real truth is nobody knows and this presents an opportunity for whoever finds the evidence for the underpinning causes and then presents practical solutions to solve them. This has been recognised by the construction industry and priorities that were fed back from the UKGBC Delivering Building Performance task group; the UK Innovate building performance project and a BSRIA workshop on Building Performance were: There was data on the performance gap but no systematic investigation of the reasons why and the magnitude of the
Figure 1: The difference between design and the building “in-use”
The “gap” seems to increase with time, again anecdotal evidence is available with no quantification of the underlying reasons; with a long term study needed to identify, qualify and quantify any affect; Health and wellbeing is associated with this effect but, as before, there is not true quantification, model or tool; as a result, a monetary value cannot be assigned to the loss/gain of productivity leading to an incomplete business case. A desk study is needed to identify knowledge gaps followed by field study producing data leading to a model/tool for quantification of productivity loss/gains The main barrier to this is quality data
from a large enough sample with full access to the building and their occupants – we have now been presented with that opportunity. What was missing is “real- life” exemplars to investigate the actual causes of the performance gap and propose practical solutions.
Figure 2: Real estate asset management cycle
NEW RESEARCH PROJECT This proposed research project is in two stages where this is the first stage which defines the methodology using trial buildings to determine the correct data to collect and the right questions to ask; with a proposed second stage rolling this out over a larger number of buildings. The initial three of eleven objectives of
this project will be: 1. Scope proposed buildings and choose a suitable exemplars for the purpose of collection and analysis of metered, asset and energy audit data
2. Using the results, from 1., propose reasons for the performance gap; produce operational and asset recommendations; model the benefits 3. Based on the learning from these trial buildings produce a methodology that can be rolled out to a larger number of buildings
BRE
www.bre.co.uk/energyguidance T: 0333 321 8811
/ ENERGYMANAGEMENT
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