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Building Construction, Environment

Energy efficiency doesn’t stack up when commercial buildings blow savings up the chimney

Boon Edam Australia 6 mins read

By Michael Fisher, Managing Director, Boon Edam Australia


Many people are familiar with the “Stack Effect” or “Chimney Effect” of energy losses occurring in their homes. It takes place when warm air rises in a house and cold air enters to replace it (or vice-versa, with conditioned cool air displacing downwards in summer).


This happens every time we open the door. It is the driving force behind that annoying and expensive draft up the chimney of houses with fireplaces, built in the more carefree times of low energy bills. And such losses – whether by chimney, open door, open window, or crack in the wall – can cost plenty on a householder’s current energy mega bill.


Well, the same thing happens – only on a much bigger and more expensive scale – in big buildings. But not so many people – architects, engineers and building managers aside – are aware of the energy waste resulting in Australia’s one million commercial buildings, including high-rise buildings, offices, hospitals, hotels, factories, corporate HQs, and shopping centres, to name a few. These big buildings can also leak money – big HVAC money – in summer and winter.


This is because of what I like to colloquially call Australia’s “loose” buildings (i.e., not very airtight), in which hot or cold air sneaks in and out through every crack, nook, and cranny it can find. And there are plenty of energy leaks in our buildings – starting with the front door, which can pour money onto the street every time it opens and blows out expensively cooled air.


Or, in winter, a wide-open door can suck in cold air, which displaces the expensively heated HVAC air inside it. This costly warmer air then disappears upstairs to find convenient openings to the outside. Often its preferred escape is up a lift shaft, which can do a great job of sucking in the outside air and blowing it out through the roof, or any other exit it can find.


The losses start with front entrances, lobbies, and vestibules, where negative pressure created by warm air pulls air through the front door every time it opens to the elements, door jambs, and cracks in walls. The reserve happens in summer when cold HVAC air is pumped out.


An answer knocking at the front door


The older the building, the worse this effect tends to be, because older builders are “looser” than modern buildings. But all big buildings suffer big losses through their entrances and interconnections – especially those with sliding and hinged doors opening wide to the elements. This happens thousands of times a day in busy buildings. If you want a first-hand experience of energy loss at work, stand in front of an air conditioned building on a hot day. The blast of cold air is wonderfully bracing, and terribly wasteful at the same time.


Placing “tight” doors between your elevator lobby and the reception area is a simple and effective first step towards addressing this problem. Scientific studies – including those of our own Federal Governmenttell us some of the tightest doors available are revolving doors – with their “Always Open, Always Closed” functionality.


They provide a superior air seal – but in a practical way that handles big traffic flows (like those at airports and hotels, which also use them to exclude noise and free up lobby space for profitable use). Their big difference, compared with sliding and hinged doors, is that they don’t continually open wide to the elements that make HVAC units work overtime to compensate. So they are a highly effective, fairly passive energy saving solution, in that they do their job of energy saving as a natural corollary of their design. Their energy-savings are built in.


So we know from experience that, in addition to protecting against weather, noise and urban pollution, these clever doors immediately mitigate energy losses that occur when the building’s HVAC system is asked to work overtime to produce hot or cold air that that otherwise blows out the front door or up through the roof.


And we know from hip pocket pain that the need for savings is becoming ever more acute, with energy prices typically rising by more than 100 per cent in recent years. Some electricity industry leaders say prices may rise again by more big steps to far and away the highest levels ever, as fossil power is phased out and the industry re-equips itself to facilitate a grid dominated by multiple green energy sources.


So why don’t all buildings have revolving door entrances if they are so effective? Good question, especially when many architects, builders and facility managers know there are energy savings to be harvested. But the problem has been quantifying the savings. Having the figures to demonstrate to the building owner that revolving doors are much more effective than wide-open doors that cost a few dollars less up front but go on to cost a heap more in service.


We at Boon Edam Australia know this passive waste occurs (passive waste in the sense that we are doing nothing about it) because we use scientifically validated methods to measure the ROI that has swung dramatically in favour of revolving door types in general, and our globally proven types in particular. The software we have available to do this – introduced to Australia and New Zealand this year – was jointly developed with one of the world’s leading technology and engineering universities, Delft University of Technology (TU Delft), which in Europe ranks right up there for sustainability and engineering credentials with the Massachusetts Institute of Technology, the MIT, in the US. Both the MIT and Delft have confirmed revolving doors save energy. But this latest software goes a step further, to place a dollar value on the energy losses we are pumping out and the gains we can make. The science is compelling when you look at the results.


The savings are displayed as kWh per month and include a simple payback time compared with a cheaper, less energy-efficient design. Greenhouse gas emissions are also shown, with a figure on CO2 reduction achieved through reduced load on HVAC with revolving doors.


Rapid Payback


The software is designed for application individually to existing or proposed buildings, which all vary greatly in scale and needs. But a general pilot study applied to Sydney, Melbourne, and Brisbane building models shows that the payback period for installing a revolving door, instead of a less energy-efficient sliding door, for example is shrinking rapidly as energy prices here accelerate quickly.


Melbourne has the quickest payback time of four years, with Brisbane next at 4.9 years and Sydney at 5.7 years because of its lower cost per kwh than the other two states. But energy costs are predicted to rise 20 per cent in Sydney and other areas of the East Coast over the year or two ahead, so the permanent sustainability advantage of revolving doors will become even more pronounced as payback times shrink more.


Our own experience, locally and globally, reveals that as energy costs rise, the payback period of energy-efficient options, such as revolving doors, has halved and is dropping. After which there is accelerating gain in energy saved that goes on for the entire period of operation of a quality revolving door, which can exceed 25 years.


Are you thinking “Well, he would say that”? And the answer is, of course I would. Because I believe it is the truth. And because I accept wholeheartedly that revolving doors by themselves are not a panacea, not a silver bullet.


But we do say they clearly deserve to be considered as a component of the green building mix, a strong, passive, and enduring element of energy saving.


We believe that at least examining the potential of revolving doors should be a no-brainer really, given that HVAC costs typically account for nearly 40 per cent of the energy consumption of multi-storey buildings in Australia and New Zealand.


Surely they need to be considered on their scientific merits as an overlooked and effective tool in our energy saving inventories. If not, why not? The science is there for everyone to see, if they want to.


About us:

With work environments becoming increasingly global and dynamic, smart, safe entry has become the centre of activity in and around many buildings. Royal Boon Edam is a global market leader in reliable entry solutions. Headquartered in the Netherlands, with 150 years of experience in engineering quality, we have gained extensive expertise in managing the transit of people through office buildings, airports, healthcare facilities, hotels, and many other types of buildings. We are focussed on providing an optimal, sustainable experience for our clients and their clients. By working together with you, our client, we help determine the exact requirements for the entry point in and around your building.

Please take a look at our range of revolving doors, security doors & portals, speed gates, tripod turnstiles, access gates and full height turnstiles to ensure the security of your entry and perimeter.

Contact details:

Jack Mallen-Cooper
PR Consultant
Whyte Public Relations
(02) 9901 4306


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