20 September 2011 – Here’s one for the books: “The single-minded pursuit of GreenStar and NABERS sustainability ratings for buildings is leading directly to compromises on indoor environmental quality and productivity.” In response the University of Sydney is building an indoor air quality environment lab to work out what’s going on, says Ashak Nathwani
In responding to the challenge of reducing greenhouse emissions, intense international attention has been focused on the way we design and operate built environments.
Major efforts are being directed at improving thermal performance of building designs and enhancing the energy efficiency of building services within them.
Both these mitigation options carry implications for the indoor environmental conditions of buildings. For example impact building occupants.
Many sustainable building design and operation strategies are pushing the comfort envelope into ranges previously discounted.
And it’s not only occupant comfort being stretched; occupant productivity is also coming under the spotlight in green buildings.
Here in Australia we’re starting to see examples where the single-minded pursuit of GreenStar and NABERS sustainability ratings for buildings is leading directly to compromises on indoor environmental quality.
The challenge for the building sector over coming years will be to strike the right balance between energy efficiency and occupant comfort.
Against this backdrop it’s not surprising that we’ve witnessed an intensification of research activity in the topic of Indoor Environmental Quality in recent years.
The international peer-reviewed literature in built environments is being flooded with papers on IEQ, the number of IEQ conferences held each year has grown dramatically.
The number of IEQ-related PhDs coming out of leading universities around the world posts solid growth from one year to the next, while the number and value of IEQ-related grant applications to funding agencies has been increasing exponentially, particularly over the last seven years.
The major themes running through all this research activity include indoor climate, lighting and day-lighting, acoustics, and indoor air quality, driven mainly by the simple fact that indoor comfort, particularly through air conditioning, typically accounts for more than half of a commercial building’s operational energy.
In response to these external drivers, The University of Sydney’s Faculty of Architecture, Design and Planning is currently building an indoor environment quality laboratory in the Wilkinson building on city road (near Newtown).
Due for completion by December 2011, the IEQ Lab will be a unique facility in which researchers can examine how the key IEQ factors – temperature, humidity, air movement, ventilation rates, air quality, daylight, artificial lighting, sound and acoustics – all interact to determine comfort, productivity and health outcomes for occupants.
The facility consists of two purpose-built rooms in which all of these indoor environmental parameters can be precisely controlled or precisely transitioned across a broad range of values, in any combination, while a sample of typical building occupants (subjects) go about their typical daily activities for an exposure time (usually a few hours each experiment), all the while registering their subjective impressions (quality ratings) on a comfort questionnaire.
The fundamental research design concept is the linkage between objective (environmental) indoor conditions to subjective magnitude estimates and assessments of those conditions.
Obviously comfort assessments on all of the human senses are inherently subjective, with significant variations from one person to the next, but by using large samples of randomly selected subjects (For example building occupants), researchers can extract a meaningful signal from all that noise.
In effect the inter-individual differences within the sample cancel each other out, rendering the cause-and-effect relationships more readily discernible.
Enormous effort is going into making the IEQ lab’s two chambers look and feel as much as possible like normal rooms, not experimental labs, so as to maximise what environmental psychologists call “experiential realism” of the simulated indoor environments.
This is to ensure that the research data collected in the lab can be generalised to real-world conditions and building occupants.
Initially the lab chambers’ fit-out will resemble grade-A commercial office spaces, but they’ve been specifically designed for maximum flexibility, so residential, industrial, retail, cinema/theatre, leisure facility, even vehicular (car, bus, train, plane) interiors can also be realistically simulated for modest reconfiguration costs.
The variety of research questions suitable for the IEQ Lab is vast, but the following list gives something of the flavour of the IEQ program at University of Sydney.
- What is comfort and how does it relate to objective indoor environmental conditions experienced within buildings?
- Are we any closer to quantifying the relationship between productivity and indoor comfort, or fresh-air ventilation rates, lighting intensities, or background noise levels? Are there synergistic interactions across the various IEQ domains in relation to productivity?
- Why do different people have different comfort expectations and requirements? Are there any gender differences, or perhaps stage-of-life differences? What about the effects of physical fitness or obesity on comfort?
- Can we quantify the differences between IEQ conditions we prefer, those that we find comfortable, and those deemed acceptable or barely tolerable?
- How do the various types of heating, ventilation and air conditioning systems affect occupant comfort? For example, what are the comfort effects of chilled-beam designs compared to, say variable air volume systems?
- What are the comfort and productivity benefits of personally controllable air conditioning systems (task conditioning like task lighting)?
- What are the optimal switch-over strategies for mixed-mode ventilation systems (those with interchangeable natural ventilation and air-conditioned modes)? Do operable windows have a meaningful role to play in energy efficient buildings? If so, how does street noise through open windows interact with indoor thermal climate and air quality issues to determine overall occupant comfort?
- Can the humble ceiling fan, combined with modest amounts of mechanically conditioned air, enhance indoor comfort for the occupants, and if so, what are the potential energy (greenhouse) dividends?
- Does lighting colour interact with thermal perception, and, if so, how can that synergy be exploited for energy conservation?
These are just a smattering of the research questions that will be tackled in the new University of Sydney IEQ Lab over coming years.
The list is obviously much longer than we have space for here, but as you can see, the research program is deliberately focused on practical problems and applications within real buildings.
Therefore the lab’s work will be highly relevant to the property industry. Indeed, industry stakeholders will have the opportunity to harness the lab’s research capabilities for specific questions of interest to their operations and the researchers will be looking to their industry partners to set priorities in the research agenda.
Heading up The University of Sydney’s IEQ Lab is Professor Richard De Dear – a world-renowned expert in this field of indoor climate and air quality.
Other academic staff from the university’s architectural and design science discipline bring expertise in thermal perception, (Dr Christhina Candido), acoustics (Dr Densil Cabrera), environmental psychology (Associate Professor Bill Martens), and sustainable design (Professor Richard Hyde).
Lighting expertise will be added to the group in coming months when the vacancy created with Professor Warren Julian’s retirement is filled.
Collectively this team represents the largest concentration of IEQ-related research personnel in the Australian university sector, and the new IEQ Lab presents an ideal platform for the group to realise the unique synergies afforded by their co-location at University of Sydney.
To perform the potential evaluations, outlined above, as well as cater for some of the likely future scenarios, a high degree of flexibility needs to be incorporated in the building services – particularly with regards to the HVAC arrangement.
In the larger IEQ chamber (Lab 1) the air conditioning system is of the variable air volume type, with flexibility to incorporate normal as well as low-temperature configurations.
Furthermore, Lab 1 can be switched over to an under-floor air distribution system with displacement ventilation.
With operable windows on two opposing walls of Lab 1 there is also the option of natural cross-flow ventilation and natural day-lighting.
The smaller chamber (Lab 2 ) will have a chilled beam system (both active and passive units), but like Lab 1 there will the option of under-floor air distribution with displacement ventilation.
There will be an outdoor corridor which will be able to simulate various ambient conditions ranging from a “Hobart” to a “Darwin”. This will enable analysis of indoor conditions with respect to different outdoor conditions.
The detailed design and documentation of the IEQ Lab’s building services has been carried out by Norman Disney & Young with input from Zoia Geller (mechanical), Dean Eislers and David Clarke (electrical).
A state-of-the-art building management and control system designed by the Australian HVAC sector’s building management system guru, Jon Clarke of NDY will be used to program the various indoor and outdoor conditions (simulated on one of the chamber’s walls) for each research set-up.
Latest building information management technology has been utilised in developing the design. Outputs from BIM, provided by Dave Foley (NDY) can be seen in the images.
The BMS system will also have the capability to log detailed records indoor environmental conditions within the occupied zones of the labs throughout each experimental exposure.
Clearly this is an ambitious project and predictably the researchers’ aspirations far exceed the financial resources allocated to the IEQ Lab by the university’s campus infrastructure services in their 2011 capital works budget.
In-kind assistance has therefore been sought from the Australian HVAC industry. The chiller has been provided by Daikin Australia, thanks to the support by John Fraser-Mifsud, national channel manager commercial business. The chilled beams and displacement diffusers have been donated by Krantz Asia-Pacific – Air Grilles Pty Ltd.
There is plenty of scope for more industry participation in the development of this unique piece of research infrastructure.
Items that are still being sourced include:
- Energy efficient light fittings – covering around 200 square metres
- Xenon type lighting that will create “outdoor” solar effect
- Induced draft coolers and condensing units
- Building Management & Control System (BMS)
- PMV Data loggers
- VOC sensors
- CO2 sensors
- VAV units
- Electric duct heaters
- Heat exchanger
- Chilled water tank 850 litres
Ashak Nathwani recently joined the University of Sydney as a part-time lecturer and has been involved in the development of different types of airconditioning systems in the two lab chambers. He recently retired from Norman Disney & Young after 33 years.