Jon Hand

Simulation-assisted control in building energy management systems

Technological advances in real-time data collection, data transfer and ever-increasing computational power are bringing simulation-assisted control and on-line fault detection and diagnosis (FDD) closer to reality than was imagined when building energy management systems (BEMSs) were introduced in the 1970s. This paper describes the development and testing of a prototype simulation-assisted controller, in which a detailed simulation program is embedded in real-time control decision making. Results from an experiment in a full-scale environmental test facility demonstrate the feasibility of predictive control using a physically-based thermal simulation program.

Building-integrated photovoltaic and thermal applications in a subtropical hotel building

Effective cooling of a PV panel is able to increase the electricity output of the solar cells. This paper describes a comparative study of three different options in applying large-scale building-integrated PV technology in a coastal city at the South China Sea. The computational model was based on a 260 m2 mono-crystalline silicon PV wall on a 30-storey hotel building. The numerical analysis was via the ESP-r building energy simulation software. The results showed that the different design options exhibit short-term electrical performance differences, but have similar long-term electricity yields. However, some design options perform much better in reducing the air-conditioning loads of the building.

Integration in building physics simulation

For more than a quarter of a century, building simulation programs have been developed to undertake non-trivial performance appraisals. In general these programs deal only with a small sub-set of the overall problem. However, advanced architectural developments require an integrated approach to design. The domains of heating, lighting, ventilation and acoustics, for example, are often closely related and it is only by taking into account their interactions that a complete understanding of building behaviour can be obtained. This paper describes some recent work to further the development of a multiple-domain approach.

Occupancy monitoring using environmental & context sensors and a hierarchical analysis framework

Saving energy in residential and commercial buildings is of great interest due to diminishing resources. Heating ventilation and air conditioning systems, and electric lighting are responsible for a significant share of energy usage, which makes it desirable to optimise their operations while maintaining user comfort. Such optimisation requires accurate occupancy estimations. In contrast to current, often invasive or unreliable methods we present an approach for accurate occupancy estimation using a wireless sensor network (WSN) that only collects non-sensitive data and a novel, hierarchical analysis method. We integrate potentially uncertain contextual information to produce occupancy estimates at different levels of granularity and provide confidence measures for effective building management. We evaluate our framework in real-world deployments and demonstrate its effectiveness and accuracy for occupancy monitoring in both low- and high-traffic area scenarios. Furthermore, we show how the system is used for analysing historical data and identify effective room misuse and thus a potential for energy saving.

Assessing energy, lighting, room acoustics, occupant comfort and environmental impacts performance of building with a single simulation program

Abstract This paper presents the developments, implementation and application of an extensive building representation which supports the holistic performance assessment of building performance within a single application. This new development supports various views of performance throughout the building life cycle in relation to performance domains such as energy consumption, lighting availability, occupant comfort (thermal, visual), room acoustics and the environmental impacts related to the construction materials and fuel streams over the whole building life span. To achieve this generic representation, the data model has three main features. Firstly, the geometry and physical model (i.e. the material composition of the geometrical elements) are decoupled to enable flexibility in the building description. Secondly, the physical model is structured to support the different building life cycle phases. Lastly, for each phase, the physical model comprises material and construction properties for each performance view. The corresponding data model has been implemented into ESP-r, an existing building simulation application, and its features have been extended in order to support room acoustics and environmental impacts. Finally, to demonstrate the applicability of the approach, a multiple-view performance assessment of an existing office building has been undertaken. It includes the assessment of the energy consumption, room acoustics, occupant comfort, and the environmental impacts. The simulation results have been compared with in situ measurements monitored in the building during the post-occupancy phase.

Photovoltaic-integrated building facades

Photovoltaic (PV) cells, when integrated within a building facade, offer the possibility of generating electric power and heat for local use or export. This paper reports on a project to investigate the practical operational efficiencies that might be delivered from such facades. The results from laboratory experiments and computer simulations are presented: the former were used to develop an empirical relationship between cell temperature and power output; the latter were undertaken to assess operational efficiencies under a range of climate conditions representative of the UK.

Performance of actively controlled domestic heat storage devices in a smart grid

Distributed, small-scale energy storage has been identified as a means of improving load factors for intermittent renewable generation and displacing the need for fossil-based backup. Domestic electric storage heaters operating within a smart grid offer high density, controllable energy storage at low cost, allowing the network operator to shift demand by charging heaters to dispose of excess supply. This paper reports monitoring outcomes and simulation studies on the first field trials of such a system, in which heaters are capable of responding to instructions from the grid to vary charging level at 15-min intervals, as well as to occupant-set controls on power output. Monitoring found significant unexpected out-of-schedule power draw and under-utilisation of storage capacity. Alternative approaches to scheduling were tested using simulations, and evaluated using metrics to quantify schedule following as well as other aspects of performance to give a balanced view of system performance to the network operator. Modern insulated storage heaters are capable of supporting load shifting for up to 48 h with minimal impact on room temperatures or demand, and with high confidence that charging schedules will be followed. However, where device controllers compete with centrally generated charge scheduling, the network will experience significant out-of-schedule power draw while occupants will experience either lower temperatures or increased cost.