When an ageing building like Wollongong’s 43 Burelli Street has plant at the end of design life, major improvements in the overall energy footprint can be achieved with strategic capex spend, according to director of Team Catalyst, PC Thomas.
He told The Fifth Estate that a thorough study of the building before developing an HVAC engineering design was a major contributor to it being on track to achieve a 4.5 star base building NABERS rating – up from 2.5 stars.
The building is a five-story plus basement commercial office constructed in 1988 with 9600 square metres of net lettable area and tenants including the Family Court, Australian Electoral Commission, Centrelink, Medicare and the NSW Office of Fair Trading. It was purchased by real estate funds manager and developer Folkestone in the middle of 2013.
A major refurbishment has been underway, including a lighting controls upgrade for the carpark, common areas and fire stairs, and an upgrade to the HVAC plant. Capital works have been completed, and post occupancy monitoring and tuning is ongoing. The building is already showing a greater than 50 per cent reduction in electricity consumption.
The project had a limited capital works budget, but high goals in terms of energy efficiency improvements. Thomas says extensive energy modelling and climatic analysis was carried out before the HVAC design was developed, and that this helped deliver a design that gives a high degree of flexibility regarding the HVAC system’s capabilities.
The climate analysis showed that the area had high humidity levels even on days under 30 degrees, so a pre-cooling coil was introduced for each of the six air handling units, which efficiently dehumidifies incoming air before it reaches office spaces. Thomas says that because the majority of the time the AHUs will be dehumidifying rather than cooling air, this innovation is delivering a substantial energy saving.
An inspection of equipment in the plant room showed that only some of it needed to be replaced, including two 25-year-old chillers, the chilled water and condenser water pumps, and the air handling units. The gas boiler was retained but refurbished, with a variable speed drive added to control the burner and improve efficiency.
Thomas says there had been evidence that tenants had been complaining about the airconditioning, and that since the upgrade, anecdotal evidence suggests the level of complaints has reduced.
There are a number of sustainability benefits an upgrade like this one can achieve, he says, including the obvious one that knocking down and replacing a building means the loss of all the embodied energy in the construction materials. They also have some inherent pluses that facilitate the process.
“These buildings have some advantages in terms of upgrading,” Thomas says.
“They have decent-sized plant rooms, which are generally not tight spaces, so it is quite easy to put modern equipment in and get it plumbed up and ready to go, then wait for an appropriate time window and switch it on, then demolish the old plant. The larger rooms give this kind of leeway.”
This is how the upgrade was managed by FDC, with new equipment put in place and commissioned during weekends and public holidays, to avoid disruption to tenants. For an owner, this gives the advantage of continuing undisturbed revenue flows from rents during refurbishment.
“Secondly, these buildings, depending on when they were built and their design, can mean less of the building [envelope] is glass. And that can mean if people want to do a facade upgrade – which is the most expensive thing you can decide to do – it is easier where there is less glass,” Thomas says.
The opportunity also exists to install systems that have flexible capabilities in terms of responding to HVAC loads, as changes in technology and equipment reduce the level of heat generated by systems such as IT and lighting.
“There is an opportunity, if you improve tenant lighting systems, the loads on the building come down quite substantially,” Thomas says.
Thomas says that because upgrades to tenant lighting are planned at Burelli St, the HVAC system design allows it to be turned down in response to lower loads.
Changes to IT technology have also been reducing heat loads, he says, with the old desktop PC with a box and CRTV monitor at 220 watts now in many offices being replaced with laptops at around 42 watts, which Thomas says generates only a fifth of the heat load. Lighting, which has gone down from an average 25 watts a square metre to 5-6 6 watts a sq m now causes a fifth of the heat gain.
“What’s left in the building then that generates heat?” Thomas says. “People.”
And this too is changing with activity-based working and flexible working reducing the human heat load in many offices also. It’s another factor that HVAC system designs need to account for.
It is imperative, Thomas says, for HVAC systems to be “right-sized” and flexible as there is every reason to assume things like heat loads from technology will continue to change.
This need for flexibility is especially crucial given the plant being installed should generally be in use for the next 20 to 25 years, so engineering design before spending capex on necessary upgrades also becomes a matter of future-proofing.
“We see a lot of projects where people replace old equipment with like for like, and this is a lost opportunity. In a 25-year-old building like this one, there is a requirement to spend capex as old equipment is getting to the end of its design life, with issues like refrigerant leaks, water leaks and HVAC not holding temperature.”
Thomas says a lot of owners or building managers also miss the opportunity by “waiting for things to fall over” and then calling the equipment supplier and buying the same plant as a replacement.
Because Folkestone did see the opportunity for betterment, Thomas says the only real additional cost for the entire project was an upfront consulting fee for technical analysis for specific HVAC upgrades.
There are still some elements of the HVAC system Thomas says can be improved to further reduce the energy footprint of tenants, such as upgrades to the floor-level controls and diffusers, which may be considered in relation to the leasing cycles.