5 June 2014 — According to sustainability consultants and energy assessors Efficient Living, there are several key pointers to achieving greater sustainability in high rise residential buildings.
Founder and managing director Tracey Cools outlined some broad guidelines.
See our companion articles:
- Residential demand means business is booming for Efficient Living
- The challenges of tall building sustainability
High rise buildings present particular challenges in the relationship between thermal comfort and ventilation, as sealing the building envelope is a key factor in controlling the indoor environment.
“With high rise on a small building footprint, you don’t always have the opportunity for natural cross-ventilation, as designing for that can result in reduced yields, and developers need to maximise the number of apartments in the building footprint in order to achieve the best return,” Ms Cools said.
“Natural cross ventilation is more [achievable] in medium rise and low rise developments.”
The sealed building envelope means issues with condensation can occur, leading to health risks. To counter this, the installation of exhaust fans in kitchens, bathrooms and laundries is important.
Other options for improving ventilation include innovative window systems. For example, a sliding door and double hung aluminium framed window system to balconies can allow l residents to have the unit breathing during the day with the double hung window open without compromising security.
“Ventilation is also a huge energy consumer in high rise, for example, in the car parks. Adding CO2 monitors and variable speed drive fans [will reduce energy use], as does using motion sensors for common area lighting,” Ms Cools said.
The vastly increased wind loading for high rise has a large impact on the ability for a high rise unit to maintain thermal comfort year-round. This means some form of mechanical cooling is necessary.
An energy-efficient solutions is to install multiple head split systems instead of ducted air conditioning systems throughout an entire dwelling, and doors to separate areas, so only the areas of the home which are currently being used are using heating or cooling energy.
Overhead fans are another important low-energy use cooling option which is regaining popularity, and one she strongly recommends, in addition to extractor fans which can pull the heat out of a home at the end of the day in summer, or a night purge systems for homes with a high thermal mass.
The big ticket energy users – lifts and lighting
One of the biggest energy users in the base building is the lifts in required for high rise residential, one solution is regenerative drive lifts which have a considerably reduced energy use.
Using LED lighting throughout common areas is becoming commonplace as it is both cheaper to run, and when sourced from a quality manufacturer, reduces maintenance replacement considerably compared to halogen globes. Ms Cools cautions there is a need to do the research, as users are relying on the quality of the company in terms of warranty and product reliability and there are all kinds of companies springing up now with new technology.
Appliances – installing efficiency
Basic appliances which most developers include in high rise apartments can also have a reduced energy footprint. Gas cook tops are installed in around 90 per cent of projects, with the high end of the market occasionally installing electric induction. Regular electric cook tops are never installed nowadays, Ms Cools said, as they are just not energy efficient.
Installing a dishwasher has become traditional, and is something the market has come to expect. Water ratings and star ratings are the guide here.
Dryers are generally installed by the developer, as there is generally no area for clothes drying in almost all high rise projects. For dryers, there are few affordable products above two stars, other than a combination condensating washer dryer.
Dual plumbing – not as popular as a good water-efficient shower
Dual plumbing is an option in BASIX. One of the solutions is to plumb the raintank back into the units for reuse.
When this first came out [in the BASIX requirements], more people took it up, but over time people realised there were cheaper and better solutions in the appliance water efficiency instead of water reuse,” Ms Cools said
“Mid-flow showers are becoming a popular option, but they need to provide a good comfortable shower, otherwise there is a likelihood people will change the product [to an inefficient high flow product]. I encourage my developers to get the product and take it home and try it. There are no reasonable low flow showers on the market that I’m aware of and this selection should be avoided.”
The benefit of residential energy monitoring
Under Building Code regulations, all buildings over 2500 square meters, including residential buildings, must have separate energy monitoring for specific systems such as lighting, lifts, airconditioning and hot water. This enables building managers to be able to pinpoint which systems may be performing less than efficiently, and decide on appropriate remediation. These can also be useful on the individual apartment scale.
“There is one thing I strongly hone in on [with multi-residential and single dwelling clients] and that is an energy meter in the home, as occupant education resulting in modified behaviour is one of the biggest triggers for [changing] energy use,” Ms Cools said.
“In multi-residential units it is [somewhat] harder [than single dwellings] because a huge amount of power is going into common areas and services which will be paid for by the strata body.”
Renewable energy systems
Solar photovoltaic systems are “one of the cheapest ways to get a building across the [required BASIX] line,” Ms Cools said.
“I also think geothermal has a huge place in sustainability.”
Geothermal systems can significantly reduce air-conditioning and water heating cost by drilling ground loops up to 150m into the earth and relying on the earth’s temperature, which is generally stable at around 18 degrees, as a baseline for heating or cooling. This is far more energy-efficient than trying to adjust ambient air temperature to the desired indoor air or hot water temperature. This type of system can combine extremely well with hydronic [in slab] heating systems, and the waste heat can be used for hot water and pool heating.
“Geothermal has really good payback periods of around two to three years in buildings with very high day time air-conditioning loads such as offices or hospitals. The latest studies show a 60 to 80 per cent increase in energy efficiency [for space heating and cooling],” she said.
The challenge with glazing
One of the more challenged – yet simple – sustainability measures in New South Wales housing is glazing systems, particularly in the single dwelling market. Ms Cools said performance glass is considered an upgrade by builders and often sold to home buyers at a vastly inflated price, which discourages uptake and means many owners decide on standard, clear single glazing.
“There is still a huge resistance to glass upgrades [in NSW], but the [materials] cost of the upgrades is actually not [substantial]. As a rule of thumb we assume a 12 per cent price increase for a window package with Smart Glass, 20 per cent increase for low-E Comfort Plus Clear and a 50 per cent increase for clear double glazing,” she explained.
“But the reality of it is, the base prices of project homes are so competitive, many companies rely on variations to make additional profits.
“I’ve seen examples of glazing upgrades being charged to home owners at two if not three times the actual cost. The window manufacturer may also be loading the price, but to a lesser extent – from our experience the builder is more often the beneficiary.
“In Victoria, where six star energy efficiency [as a mandatory minimum for residential builds] has been in place for some time, the true cost of glass upgrades seems to be getting passed on, so hopefully NSW will start to follow this trend sooner rather than later.”
Fudging the figures for BASIX an issue
Another area where some builders are letting the sustainability side down is genuine compliance during construction with the BASIX requirements. The Fifth Estate has heard from various sources there is a level of non-compliance occurring on some projects, and Ms Cools confirms this.
“The DIY glass calculators where multiple windows are grouped are easily manipulated for reduced cost compliance,” she said.
Ms Cools works closely with private certifiers, and often gets called in when a project has failed to achieve Occupancy certification from the local authorities, because the certifier has discovered the BASIX compliance was not what it was supposed to be.
“On site compliance is becoming more of an issue. The certifiers are [now] checking on it. And the new BASIX certification will make it easier for them to see what is right and what is wrong,” Ms Cools said, “which is a great win for home owners.”
“We are often called out on site for compliance, when the council is saying it is not what was specified with the development approval. When we get in and find it is not right, we will either propose alternative solutions, or where that is not possible and the [issue] is deal-breaking and will result in the project not obtaining an occupancy certificate, a retrofit has to be done.”
This of course then adds to the cost of the project – whereas embedding sustainability from the outset can be both cost-effective, and add to resale value.
Low rise or high rise – sustainability equals greater value
“[Developers and owners] are only just in New South Wales starting to understand the idea that sustainability gives a higher resale value, and that the investment [in energy-efficiency] will come back on resale,” she said.
“Mirvac’s Harold Park project [which the firm worked on], which aimed for 25 per cent above BASIX is a good example. It has been a marketing edge for Mirvac, and it also changes the type of customers they have for the properties, which changes the type of community [which evolves there]. Lend Lease’s Rouse Hill is also an amazing example of that.”
While this is extremely positive, Ms Cools observed that the general belief is the residential sector is achieving an average of around five star thermal comfort across New South Wales, whereas the reality is some projects get a pass with results as low as 3.5 stars. In other words, most projects are only doing the bare minimum required in terms of achieving energy efficiency performance.
They could be achieving far more
Ms Cools described a balancing act between pushing the boundaries of sustainability and respecting the boundaries imposed by budgets.
“You can’t push past the budget,” she said, “or the recommendations will get value engineered out before the project hits site.
“It’s a great ideal to target an eight star home, but if you run the numbers, our clients will actually end up with a more efficient home if they target six stars and spend the remaining budget on improved efficiency with the electrical inclusions.”