Post Occupancy Evaluation
Senior Building Performance Engineer
Max Fordham LLP
What is POE?
A Post Occupancy Evaluation (POE) is the process of obtaining feedback on a building's performance in use and generally occurs when the occupants have settled into building.
POE is a method used to help find out how well the building is working. By “work” we mean:
- What do people think about the building?
- Are people comfortable?
- Do they understand how to use the building?
- How does the building perform in terms of energy and carbon emissions?
- Are the internal environmental conditions healthy and promote wellbeing and productivity?
A POE will also help to highlight any teething problems that can be addressed and solved, identify any gaps in communication and understanding that impact on the building operation and provide lessons that can be used to improve design and procurement on future projects. The diagram below shows how POE fits into the construction process. It is an essential part of the Soft Landings process.
There is no one standard methodology of POE. The method(s) should be selected to suit the needs of the project. POE means different things to different people.
However, in general the following areas will be covered:
- Energy review
- Observe the building in use
- Talk to people: either informally or through a survey/interview
1: Energy review
At the very least, the total yearly energy consumption for the building should be measured and reviewed. To do this at the minimum the main electricity and potentially gas meters, should be read each year. This data can then be compared to benchmarks and design predictions to see how well the building performs. Also, if aiming for net zero verification, this data can be used to calculate the carbon footprint of the building and whether any carbon offsets are required.
A more detailed energy review can be completed if monthly meter readings, half hourly data or sub-meter readings are available.
The graph below shows an example of a breakdown of monthly energy data for a primary school. In this case the data was used during regular meetings to optimise the performance of the building. It’s useful to get this sort of energy meter data as it tells you where energy is being used and when. Ideally drilling down using half hourly data can tell you even more. It’s then about using the data to make positive changes to help drive down consumption.
2: Observe the building
Useful lessons learnt can be established by walking through the building once in use and making observations. If doing a more detailed POE the BMS should also be reviewed; this would include reviewing heating/cooling set points, time schedules, any historic records of internal temperatures and air quality, and general operation of plant equipment e.g. historic boiler flow temperatures etc.
3: Talk to people
The best way to assess how a building affects occupants is to ask them – they know better than anyone else. There are various ways you can do this; informal discussions, structured interviews or formal surveys.
A few established formal occupant satisfaction surveys which provide benchmarking include:
- The Building Use Studies (BUS) methodology
- The Leesman Index
These are generally focussed on offices, but the BUS methodology also has versions which can be used on other building types. BUS Partners can administer the surveys.
CIBSE have also produced questionnaires, including one for schools featured in CIBSE TM57.
Bespoke surveys can be produced, which can often be made up of tweaking existing surveys.
The role POE can play in the delivery of NZC buildings
POE is essential to achieve a net zero carbon building; you must measure the actual operational energy used by a building to know what the true operational carbon footprint of that building is. Also, if aiming for Net Zero Carbon verification you must know this value to understand how much (if any) you need to offset for your building to be verified as Net Zero Carbon.
POE is also very important as it is a method to gather feedback and lessons learnt on buildings which can be used to improve design on future projects. The more designers, clients and other members of project teams learn about how their buildings perform in use, the better their next buildings are likely to be in terms of energy use and meeting the client’s needs.
POEs are required as part of the RIBA 2020 plan of work, RIBA 2030 Climate Challenge and RIBA Sustainable Outcomes Guide 2019.