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MMMB Research Seminar
August 28, 2019 @ 11:30 am - 12:30 pm
Near-Roof Air Temperatures: Modelling the Implications for HVAC Performance and Cool Roofs
Conventionally in building performance simulations (BPS), it is assumed that air entering outdoor air-conditioning equipment is at the outdoor ‘ambient’ temperature, obtained from a weather file. However, significant spatial variations exist in outdoor air temperature fields, especially within the thermal boundary layers that form near exposed surfaces like roofs.
Experiments were conducted at three large-footprint shopping centre buildings, to characterise the above-roof temperature field. An empirical model was derived from the experimental data, and applied in BPS of a shopping centre with rooftop HVAC equipment in seven Australian climates. In these cases, the electricity savings and gas ‘penalties’ attributable to cool roofs would have been underestimated by 44–85% (61% on average) if near-roof air temperature variations had not been modelled accurately.
Alan Green (University of Wollongong)
Alan Green is a Research Fellow, working at the Sustainable Buildings Research Centre (SBRC). He has a keen interest in fluid dynamics, which has taken him to work alongside researchers in the Netherlands, UK, USA and Portugal. Much of his work has focused on the design of experiments and equipment for studies of wind, heat transfer, and multi-phase flows, as well as computational fluid dynamics (CFD) simulation techniques.
- Building resilience to bushfire
– Bushfire sprinkler systems.
– Retrofit technologies for existing buildings.
– Quantifying building resilience.
- Building thermal performance
– Experimental methods and equipment.
– Adaptive façade systems.
– Cool roofs and near-roof air temperature fields.
– Natural ventilation.
– Innovative heating ventilation and air-conditioning (HVAC).
- Fluid dynamics in general
– Experimental techniques.
– High-speed videography and image analysis.
– Computational fluid dynamics (CFD).
– Buoyancy-driven flows.
– Multiphase flows.
– Atmospheric boundary layer flow.
Benchmarking thermal performance of buildings and identifying preferred thermal conditions with highly deployable IoT devices.
Low cost, network-based, pervasive sensing devices that capture a range of indoor environmental parameters were successfully developed and deployed in two large mechanically ventilated buildings in Sydney and in Wollongong in Australia. The devices could provide information over the internet for the indoor environment of the buildings at high spatial and temporal resolutions and could also capture occupant expressions of preferences for the indoor thermal environment. The presentation discusses findings from the monitoring data and the real-time occupant responses that were collected between March/2017 and October/2018. The analysis includes records from approximately 1450 real-time expressions of thermal preferences from the occupants of the two buildings and more than 5.5 million time stamp rows that contained sets of indoor environmental quality data. The project demonstrates a low-cost method for benchmarking buildings with each other and providing the means of communicating the often-unknown occupant requirements to facility managers. A final analysis is given for the potential benefits that could be gained in open plan offices with flexible desk allocation arrangements by using the data from the above devices to directly communicate suggestions for alternative locations to the occupants who express a preference for a different thermal environment.
I am a Senior Lecturer at the Sustainable Buildings Research Centre (SBRC). My broader research aims to the development of tools and technologies that will lead to improved built environments that reduce the impacts on the energy resources and the environment while providing healthy and comfortable indoor spaces for the occupants. I am particularly interested in the development and validation of whole building energy simulation programs that enable a rigorous quantification of metrics associated with the above aim. My research projects and activities also include research on developing and embedding IoT devices in buildings to enable a better understanding of building operations at high spatial and temporal resolutions.
Building Energy Simulation; Building Services Engineering; IoT for Sustainability; Energy Efficient and Low Energy Building Design; Ventilation; Renewable Energy Systems; Heat and Mass Transfer.