Uncertainty and sensitivity analyses of operational errors in air handling units and unexpected user behavior for energy efficiency and thermal comfort

Resource scarcity and anthropogenic climate change require the reduction of performance gaps in existing buildings. In addition to unexpected user behavior, performance gaps are primarily caused by the technical gap due to operational errors in building technology. The main objective of this paper is to quantify model input uncertainty incorporating uncertain boundary conditions in terms of operational errors using thermo-dynamic building performance simulations and to identify the most relevant input parameters for the performance gaps in air conditioning systems by means of sensitivity analyses. Model input uncertainty is stochastically determined using Monte-Carlo Simulations to calculate the target values “primary energy demand” as well as “over- and under-temperature degree hours” for an office building. Selected parameters are simulated in a specific uncertainty and sensitivity analyses using the Sobol’ and Jansen estimators, which distinguish between a direct influence on the target variables and interactions between the parameters. The methodology requires a selection process, which is carried out as part of relative uncertainty and relative sensitivity analyses. Furthermore, the operational errors are compared with construction factors as well as building physics inputs and design parameters for building technology systems to show their reciprocal effects as part of a comprehensive investigation. The main findings of this paper are that operational errors in air conditioning systems play an essential role in decreasing energy efficiency and thermal comfort, but do not warrant the significance of certain construction factors as well as setpoints in building technology. Moreover, the impact of operational errors on thermal overheating of the building investigated is minor compared to other targets that cause greater model input uncertainty.

Thinking inside the box: new ways of considering energy consumption in a multi-user agency-constrained environment

Reductions in end-use energy imply some level of technological and behavioural change — yet there are marked differences in the balance between them. Moreover, the ways in which these influences can combine and mutually shape each other are complex, especially where multiple users interact within the same environment. A socio-technical perspective has gradually become more popular in building energy research in recent years, as it widens the focus beyond technology to include practices, infrastructure, markets, policies, social norms, and cultural meanings; however, there is very little knowledge on how this interplay works — particularly in a non-domestic environment. In this paper, we attempt to enhance the understanding of ‘social ordering of choices, problems and practice’ (Guy & Shove, 2000, p. 139) within a retail environment — and how these are competing when it comes to decisions about energy consumption. Using a longitudinal multi-methodological case study approach, this paper aims to explicate the socio-technical context within which energy consumption is considered by various actors in a large supermarket given that these actors have other behaviours (e.g. convenience, profit) as a priority and that the retail environment is agency constrained (i.e. shoppers, employees can hardly do anything individually to affect energy consumption). Using mixed-reality platform, we visualised socio-technical interactions, thus also visualising the decisions on where energy efficiency interventions could be made, what needs to be considered, and how this differs from different perspectives. Priorities that often remain ‘unspoken’ become visible — and thus provide a powerful foundation for the discussion about the consequences of an intervention there and then thus reduce the complexity of discussions and keeping crucial information available during the entire discussion process.