An occupant-centric assessment of the building performance gap in low utilisation, higher education facilities

  • Stephen Oliver

Student thesis: Master's Thesis


Seminal literature advocates that the occupants of buildings are the real consumers ofenergy, not the buildings. While this is a helpful philosophy for design and retrofit analysis, it is not entirely accommodating of operational building energy demand. An optimistic amendment would suggest that it is the needs of people that consume energy rather than buildings, for nondomestic buildings at least. However, needs in operation are not guaranteed to correlate with simulation, and servicing of needs is not bound to the real occupant presence. The presence of the people, whose needs exist in a given discrete space is not a prerequisite of energy consumption. In broader terms of occupancy, the observation is absent from the nature of consuming services' relationships with occupants and the activities that drive the second-order interests. That is, what constitutes as needs of one occupant is not necessarily equivalent of identical needs of another. These factors cause great concern for retrofit decision-making and invariably make a significant contribution to the building performance gap. Given the presumption of needs' role in building energy consumption, it appears that the industry must revise its current definitions of what constitutes as an occupant and how efficiency is measured. After all, an ideal system is still inefficient, if its operation has no utility. Further and higher education facilities are notably sensitive to these concerns. Where the assumption that needs exist in design models is known typically to deviate by 73% in teaching spaces, in the United Kingdom. However, they are also uniquely equipped for stabilising their utilisation through strict class allocation planning. The difference in utilisation when mapped to zones in EnergyPlus can profoundly affect how a simulated building behaves. These changes to simulated behaviour can redefine the retrofit solution space. Without strict heating management through registration of periods of nonzero density presence to a building management system, over two-thirds of needs do not exist. This study aims to demonstrate the severity of the presence simulation gap and provide a case for heat management as a precursor for conventional retrofit analysis. It also aims to determine whether gaps exist in the current occupant ontologies. A registration system-led occupancy modelling tool for EnergyPlus is developed to explore divergence from standardised and real utilisation to simulated behaviours under known conditions. The tool is tested through two virtual cases under different building states by assessing real-world utilisation of the teaching spaces for two years' weather data and six Schedule-Climate scenarios. Three retrofit options encompassing heating management, lighting and boiler replacement are simulated and presented under each Schedule-Climate scenario. All results form building energy modelling are considered in terms of emissions, net energy and operation costs. Retrofit results are assessed using discounted cash flow analysis at the Green Book suggested discount rate. The entire solution space is procedurally generated by a bespoke library which integrates EnergyPlus and data analytics tools. The experimentation results show the severity of the presence and presence-bound scheduling simulations gaps. It is shown simulated heating energy demand is dependent on latent gains to the extent that when heating schedules are decoupled from presence as per the real world, retrofitting lighting will have an adverse effect on building energy performance. The results proceed to explore the underlying relationship between heating and lighting energy demand, occupancy and net building energy demand. This is demonstrated through presentation of disaggregated internal gains and determining the ratio of energy consumption to net energy demand for combined lighting and heating. The experimentation results are concluded by presentation of result from constant-efficacy lighting retrofits from eighty Schedule-Climate scenarios. Referencing the low utilisation from the registration system and out-of-design presence, the discussion proposes how measuring efficiency in terms of met needs has merit in the higher education sector. Findings from the literature review and consideration of the heterogeneous utilisation is used to explore several new ontologies which bridge the gap between virtual and real occupants.The thesis which is themed on a previous publication proposes a philosophical framing of energy consumption in low-utilisation buildings. It makes several suggestions for future research ultimately concluding that retrofit analysis should focus on robust mediocrity over simulated optimality of proposals.
Date of Award14 Feb 2020
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorFarzad Pour Rahimian (Supervisor) & Andrew Agapiou (Supervisor)

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