Steady state or dynamic simulation models? January 16, 2012

XCO2 Energy recently participated in the Post Occupancy Evaluation and Dynamic Simulation workshop held at London South Bank University. The event was organised by the Building Simulation Group and was well attended by a wide range of architects and engineers with an interest and experience in POE.

The workshop covered a wide range of issues including current UK regulations on the energy and sustainability of buildings, the need for building performance evaluations and discussions on the performance of Passivhaus in reality.

One of the key figures behind the Usable Buildings initiative, Bill Bordass, gave a talk on the subject of POE and made an important point that the designs of buildings and their systems need to be kept simple in order for them to work in reality. He stated that a good client, brief, team and specialist support were essential in ensuring a building performs efficiently and as intended by the designer and that from the research he has done in the field he has found that generally the more renewables specified in buildings (in particular schools) the worse performing they are in terms of energy use and efficiency.

Other speakers also attended from BSRIA and engineering firms, sparking discussions on results of post occupancy evaluations and the use of PassivHaus in generating sustainable buildings.

A main point of discussion was whether steady state models eg. SAP, SBEM and PassivHaus, were accurate enough to model energy reductions or whether dynamic simulation models (DSMs) would be better used to predict a building’s performance. Some of the attendees felt that more reliable results through steady state models could be achieved if the accuracy of the input data was improved. However supporters of DSMs felt that steady state models could never be accurate enough to reflect the buildings response to the local climate and did not contain some of the main energy uses such as appliances and plug loads.

At XCO2 we feel that whilst there is a large gap between the designed performance and actual performance of buildings in terms of energy use, more needs to be done to accurately predict energy consumption. Until the performance gap is reduced both the steady state models and DSMs should be modelled carefully and with the occupants in mind to better predict the final energy use of the buildings designed.

Let us know what you have to say on the subject.