Engineering school buildings where IEQ supports student IQ
Jason WrenView bio
If your school days memories include classrooms that were stuffy and sweaty in summer, and miserable and drafty in winter, you’re not alone. All too frequently, Australian schools have been uncomfortable, badly ventilated teaching and learning spaces. The COVID-19 pandemic has accelerated the movement towards improvement ventilation with a focus on ensuring levels of fresh air that reduce the likelihood of airborne contagion.
Indoor Environment Quality (IEQ) is a key focus of building services engineering, and there are several innovative ways to deliver good IEQ that also ensure low operating costs for education departments.
Our current work on a Melbourne school that is incorporating Passive House design principles is creating an extremely energy-efficient school. Our design ensures the building will have improved occupant comfort while requiring significantly less energy than a conventional school building delivered to minimum building code performance requirements. That translates into a substantial bottom-line saving on operating costs.
The design incorporates a well-sealed building envelope, with heat recovery ventilation ducted to provide filtered, conditioned 100% fresh air to every classroom. The design also features CO2 monitors linked to the Building Management System: this automates the ventilation, heating, and cooling requirements, based on ambient conditions and occupancy levels.
We also explored a variety of controls options ahead of final design. This includes flexibility to allow the system to intuitively recognise if the windows are open on favourable days. This turns off heating or cooling while supplying unconditioned fresh air through a Heat Recovery Ventilator (HRV) with thermal wheel heat exchanger and a bypass for when ambient temperatures are suitable.
The project also demonstrates that the principles of Passive House – designing for minimal energy use and optimum IEQ - are valuable for any project, not just residential homes.
Another approach we have used on multiple projects is the thermal labyrinth. This is a technology that has been around for centuries, but the new iteration comes with some added smarts.
The labyrinth structure tempers outside air, between five and eight degrees, considerably reducing the amount of energy required for mechanical systems to heat or cool air to spaces to comfort levels. The solid nature of its construction means it will last for the life of a building – if not longer – and the structure requires no significant maintenance apart from the fan to draw the air slowly through the meandering path of the labyrinth.
On one of our recent school projects, the labyrinth is used for both daytime tempering of fresh air for the school HVAC system and for night purging of all the classrooms to ensure air circulation. The night purge also recharges the labyrinth if it has gained excessive heat through the day.
The BMS is the ‘brains’ that connects the dots. This includes operating louvre windows that utilise the principles of thermal stratification for non-mechanical air out-take as they are located at a specific height for security reasons. A weather station linked to the BMS ensures the louvres are not open when it rains. The whole project shows how sophisticated engineering thinking, modelling and innovative design can be delivered in a relatively simple kit of parts. This approach ensures a low maintenance system, excellent IEQ and fresh air levels, and low running costs.
With our education projects we always look to consider the ‘educational benefits’ of our designs. This includes a display screen located somewhere students can see real-time energy use data, solar PV generation (if the school has solar panels), and other information. For example, through the use of check meters linked to the BMS, it can show how much water has been saved by utilising harvested stormwater from the roof drainage, instead of potable water. This helps students engage with their building and develop energy efficiency literacy – so we are raising their energy IQ and supporting IEQ too.
CO2 monitors are another fundamental piece of the school IEQ solution. They enable the BMS to see an increase in the number of occupants or a rise in the level of activity in a classroom and respond by increasing the amount of fresh entering the space, improving the air quality to appropriate levels. CO2 sensors are going to be more popular now in this near post Covid world.
A key direction we are taking with our approach to building services and IEQ in our projects, and particularly in schools, is all-electric. The Victorian Government already has as part of its school design guidelines for new schools a gas-free approach, and a policy of reducing or eliminating gas across all its school sites.
This is where a multi-disciplinary approach yields the best results. Going all-electric has a direct impact on hydraulics, mechanical and electrical services. One of the positives of going gas-free is that electric solutions for hot water and space heating such as electric heat pump technology are much less costly to operate. And of course, you eliminate explosive flammability risks and the need to design for gas-standard ventilation.
As engineering design and advisory experts, we are conscious that solutions must also be robust and simple to operate: once a school is built, it needs to be easily adopted and understood by incoming staff. Systems need to be well-documented and straight forward to operate. If they are a little more complex these days - such as a Passive Haus designed school - it is important to get the client’s “buy in” and make sure they understand the systems, how to operate them and most importantly how to maintain them. As consultants, we need to carry out a thorough review of the operation and maintenance manuals created by the contractors to ensure the information can be used by a lay person if in future there is an issue with any of their building services.
This makes it important for us to be user-centred in our thinking. By considering occupancy comfort, energy efficiency, ease of use and safety, we design educational facilities that are helping our next generation of thought leaders.