On January 11, Sydney had its muggiest day on record, with the hourly dew point reaching a record temperature of 25.9 degrees Celsius and humidity weighing in at 94 percent.
But the office workers at architecture practice Smart Design Studio, in the inner-southern Sydney suburb of Alexandria, did not experience a temperature higher than 26 degrees, and it wasn’t due to the whir and hum-drum of air conditioning.
Innovate in a space with climate restrictions
Smart Design Studio founder and creative director William Smart had heard about under-floor heating being used as an HVAC alternative in Europe. When it came time to build a new office space for his team in Alexandria, he enlisted the help of an underfloor cooling consultant, however, there was a roadblock regarding delivery.
“He initially said it wouldn’t work in Sydney, it’s just too humid,” recalls Smart. Melbourne’s dry climate may allow it, he was told, but Sydney’s humidity is just too much of a hurdle to overcome.
Informing an office in frequently humid Sydney that summer will be without air conditioning could be fraught with peril. However, scepticism was not directed towards Smart’s desire to implement underfloor cooling.
“There was a resounding support for it and an understanding that on hot days, it would be warmer, and we would need to find ways to manage,” says Smart.
A calm, ‘whisper quiet’ and cool office
The team unpacked the limitations of underfloor cooling and brainstormed tips and tricks to combat the intense humidity – wearing lighter and cooler clothing in the office, staff kicking off their shoes and allowing their feet to be cooled on the tiled floor, and ensuring a large number of in-house fans.
Two years on from the delivery of the practice’s office, Smart speaks to Facility Management of a serene and “whisper quiet” office drenched in natural light and never hotter than 26 degrees, with “incredibly low” energy consumption to boot. But what is underfloor heating and cooling? How can it function effectively in Australian households?
Quest to keep cool without warming the world
Incentivised to reduce energy consumption and innovate a space in a climate prone to unshakeable humidity, Smart decided to design a new office space that would operate without air conditioning.
The office space in Alexandria is an 800 square-metre open-plan former warehouse building boasting generous volumes of air, a sawtooth roof, delicate trusses, intact façades and seven-metre-high ceilings at some points.
The climate control magic is noted in the floor – made up of a concrete slab covered with tiles, with hydronic pipes containing water that either heats the floor in winter or chills the floor in summer. On moderate days, Smart admits, it does not really function.
“80 percent of the time it’s not really functioning, and then 20 percent of the time it’s either heating or cooling the floor to different levels,” says Smart.
In addition to an underfloor cooling and heating system, Smart was eager to have a continuous stream of fresh air and natural light in the office to allow workers to feel comfortable and content, and subsequently increase productivity and overall office wellbeing.
A life-size and cost-effective esky
An in-built function to gauge the next day’s weather means the system knows to either cool or warm the office overnight in preparation. The blinds and windows are also operated by the same system.
“In summer, winter and the in-between months, the system goes through a night perch mode and opens all the high level windows in the secure parts of the building from around 10pm until three or four in the morning,” says Smart.
In the morning, the windows will either stay open or closed depending on the conditions of the day. Smart says the building functions in a manner similar to an esky.
“In winter you let the sun in by having the blinds up. In summer, you put the blinds down and keep the sun out. You don’t want the hot air to escape in winter, or the hot air to come into the space in the summer,” says Smart.
Low energy consumption
The effectiveness of underfloor cooling and heating is also bolstered by solar panels – 260 on the roof – a light-coloured roof and cross ventilation.
Office workers relish not breathing in filtered air through an air conditioning unit, and Smart rejoices in the minimal energy consumption. In peak loads, the consumption is very low, and in summer when the sun is shining in all its brilliance, there is a sufficient amount of energy gained from the solar panels to operate the underfloor cooling.
Smart says there’s definitely still bursts of mugginess in the office, however, over the course of the year it’s insignificant. Sporadic seasonal discomfort is worth the long term gain of a pleasant office environment and low energy bills.
A small and damp sacrifice
On the aforementioned record dew point day in Sydney, everything that was cooler than 25.9 degrees would inevitably condensate, which meant the cool tiled floors at Smart Design Studio started to resemble a slip-and-slide, and fans were operating at the quickest speed to make the condensation evaporate.
This is a small but manageable limitation of the system, says Smart.
“On this day, our floors were getting wet, and you would take a bottle out of the fridge and it would get condensation on it,” says Smart. “We needed to keep the floor cool to cool the space, but mugginess means condensation, so that’s where the system slightly falls down.”
Avoid opening the oven door
Can underfloor cooling and heating systems be implemented in residential buildings? Smart Design Studio has designed houses with underfloor systems, but it depends on a few factors.
“I think the system works best when coupled with an underperforming air conditioning system, because what happens is that the system absorbs the base load,” says Smart.
Underfloor cooling might reduce an indoor temperature of 35 degrees to 26 degrees, and then the air conditioning will decrease it more to 24 degrees.
Smart says people fall short when trying to cool down facilities or houses by relying on a method that feels the most natural, yet is an unsustainable band-aid solution.
“I think the biggest mistake is opening a house when it’s a hot day– it’s like opening an oven door, you’re letting the heat from the oven into the space,” says Smart. And while it’s momentarily satisfying to feel a slight cool breeze, it’s ineffective in dry heat climates. “It’s better to just close the doors and have a fan running.”
Double glazed the way to go
An additional misconception Smart addresses is that glass has the power to cool down a space, when in reality it’s actually a “poor insulator and a poor material for the internal environment,” according to Smart. A glass-heavy space translates to a loss of heat in winter and crippling heat in summer.
If opting for glass, double or triple-glazed windows are preferable, and bolstered in functionality by pairing them with ceiling insulation – noted in Smart Design Studios’ office, which has high volumes of insulation, a light-coloured roof and solar panels.
An investment rather than a cost
Underfloor cooling demonstrates how incorporating sustainable building practices into a build can be perceived as an investment rather than a cost. Smart Design Studio celebrates this tweaking of terminology and definitions, as attitudinal change is the key to making those resistant to ‘green builds’ jump on board.
“If you ask architects what their biggest challenge is, it will be trying to meet a client’s brief and expectations and manage that with the budget – and you don’t have to have double glazing or underfloor cooling, but it is undeniably better, and then it becomes a matter of value,” says Smart.
Underfloor cooling and double glazing are more expensive than installing air conditioning, as you have to lay pipes and sweep the floor, or front a hefty amount if selecting double-glazed windows, however, Smart says the payback is eternal.
“If you were to invest approximately $100,000 in moving to double-glazed windows, you’d be likely to save $10,000 a year in energy, so in terms of investment, that would pay back its own cost in 10 years,” says Smart.
Thoughtful and purposeful passive cooling
If air conditioning is still a cherished and unmovable feature in your facility or home, Smart recommends trialling temperature fluctuation as an energy saver.
“You can relax some of the parameters of air conditioning to save on costs,” says Smart.
Smart also advises people to release heat from houses and facilities at night by keeping the windows open.
“If you can release hot air at night, that gives eight hours of cooling time, and thermal mass such as bricks or concrete also provide cooling and reduce running costs,” says Smart.
Opening windows does let debris such as leaves and insects into the space, so facilities and houses need to install protection agains such debris and embrace the challenges that come from allowing windows to stay open.
“It means you have to be thoughtful about what will work for the space,” says Smart.
An intimate understanding of the space, surrounding environment and climate is a reliable weapon to take into battle, and will allow people to anticipate what is required if opting for passive cooling methods.
Photography of Smart Design Studio’s office by Romello Pereira.