Central systems

Common clothes washers

Applies to multi-dwelling developments only.

If you are installing a common area laundry with a shared clothes washing machine, nominate the energy rating (in stars) of the appliance.

Remember to keep in mind the water efficiency rating in the Water section. Higher water efficiency improves your energy score through reduced hot water consumption.

Common clothes dryers

Applies to multi-dwelling developments only.

BASIX recognizes the following types of clothes dryers in common areas:

  • gas heated; and
  • electric– with the nominated star rating.

A gas clothes dryer will give you the highest BASIX score. If installing a gas clothes dryer you will need to flue the exhaust. Gas clothes dryers must comply with AS 4554-2002 (AG 104-2002): Gas laundry dryers.

If installing an electric clothes dryer, install a dryer with the highest star rating possible.

Using cogeneration heat from another system may be viable to assist in drying clothes. You will need to apply for an alternative assessment if seriously considering this option.

Active power factor correction

Active power factor correction means the correction of the power factor of an electrical system by equipment in order to reduce power losses in the supply of electricity to that system.

The power factor of an AC power system means the ratio of "real" power (measured in kW) to "apparent" power (measured in VA).

Power factor is always between 0 and 1. Inductive loads such as transformers and motors, or capacitative loads can reduce power factor. Low power factor systems (0.75 and less) incur greater losses.

Active power factor correction will minimise transmission line losses and reduce greenhouse gas emissions. With most electricity contracts, it will also reduce the monthly demand charge paid.

Active power factor correction is only relevant for mid and high-rise buildings with large inductive loads and therefore low power factor.

Energy sources for heating systems

Energy sources for heating systems available in BASIX include:

  • Co-generation heat
  • Gas heat pump (air sourced reverse cycle air conditioning)
  • Electric heat pump (air sourced reverse cycle air conditioning)
  • Electric driven compressor + air sourced evaporator
  • Gas driven compressor + air sourced evaporator
  • Gas boiler
  • Electric boiler

Note: Options vary depending on the heating system selected

Central heating systems

A central heating system heats more than one dwelling (generally all dwellings). In multi-dwelling developments, BASIX recognises the following types of central heating systems.

Fan coil and heated water

Dwelling heating unit(s) contain fan and heating coil (typically integrated with cooling fan coil unit); medium temperature (typically 60-80oC) heating water is piped from central heating plant)  

Fan coil and electric resistance

Heating provided by electric resistance elements located in the dwelling cooling unit or ductwork

Radiators and heated water

Dwelling heating provided by radiators; medium temperature (typically 60-80oC) heating water that is piped from central heating plant

Water source packaged units and heated water

Dwelling air conditioning unit(s) contain fan, cooling coil and compressor; heat is extracted from low temperature (typically 20-30oC) water piped from central heating plant

Water source packaged units and electric resistance

Heating provided by electric resistance elements located in the dwelling cooling unit or ductwork 

Variable refrigerant volume units

Dwelling air conditioning unit(s) contain fan and heating coils; hot refrigerant gas is piped from central compressors and heat source plant. 

Central cooling systems

A central cooling system is a system that cools more than one dwelling (generally all dwellings). In multi-dwelling developments, BASIX recognises the following types of central cooling systems:

  • chilled water fan coil units:
    (dwelling air conditioning unit(s) that contain fan and cooling coil; chilled water is piped from the central cooling and heat rejection plant).
  • water source packaged units:
    (dwelling air conditioning unit(s) that contain fan, cooling coil and compressor; cooling water is piped from central heat rejection plant).
  • variable refrigerant volume units:
    (dwelling air conditioning unit(s) that contain fan and cooling coil; refrigerant is piped from the central compressors and the heat rejection plant).

It is highly recommended that the design and installation of a central cooling and/or heating system is carried out in association with a qualified mechanical or HVAC (Heating, Cooling and Air Conditioning) engineer or technical specialist. They will help you with some of the information required for BASIX.

Further information

The NSW Public Health Act requires periodic inspection and testing of cooling towers to minimise risk of legionella. For more information see NSW Health Fact Sheet on Legionalla and Legionaire's Disease.

Saunas

For multi-dwelling developments, BASIX assesses the energy usage of saunas based on:

  • the heating source for the sauna; and
  • the sauna efficiency measure.

BASIX does not apply to saunas installed as part of new single-unit homes or as part of an alteration to an existing home.

Sauna heat sources

BASIX recognises the following heat sources for saunas:

  • Electric infrared
  • Gas
  • Electric resistance

Electric infared or gas saunas are the most efficient types and will give a higher BASIX score than saunas heated with electric resistance.

Sauna efficiency measures

BASIX recognises the following efficiency measures for saunas:

  • Push button timer (manual push button which switches sauna on for a set period of time, with an automatic off)
  • Controlled by BMS (Building management system) (sauna automatically turned on and off according to a preset schedule as part of a computer driven building management system)
  • Stand-by function (sauna goes onto stand-by mode when not in use)

The most efficient measure for saunas is the push button timer, and the least efficient measure is none.

Pools and spas

BASIX assesses the energy used for pools and spas based on:

  • the type of pool heating;
  • whether or not the pool pump will be controlled by a timer;
  • the type of spa heating; and
  • whether or not the spa pump will be controlled by a timer.

Other pool and spa details (including size and whether or not there will be a cover) are required in the water section of BASIX.

See also Pools and Outdoor Spas (Water Use)

Lifts

BASIX recognises the following lift systems:

  • Geared traction lift with VVAC motor– geared traction or cable lift that is powered with a variable voltage alternating current motor;
  • Gearless traction lift with VVVF motor– gearless traction or cable lift that is powered with a variable voltage, variable frequency motor; and
  • Hydraulic lift.

You will need to nominate the number of storeys served by each lift.

Drive types

A traction lift is powered by an electric motor (AC or DC) which is coupled to the hoisting mechanism through a reduction (worm) gear. The motion of the car is obtained through traction between the suspension ropes and the driving sheave. This is also known as a cable lift.

A hydraulic lift is driven by a pump which raises or lowers the lift car by varying the oil pressure in a ram. The pump is driven by an electric motor.

As a general rule of thumb, gearless traction lifts are more efficient than geared traction lifts. Traction lifts are also more efficient than hydraulic lifts, as they have a counterweight and do not waste heat by heating the oil used as the hydraulic medium.

Motor and controller types

There are several types of electric drives: AC 2-speed, AC Variable Voltage, AC Variable Voltage Variable Frequency (VVF), DC static drive and DC Ward-Leonard system.

With AC Variable Voltage Variable Frequency Drive (VVVF), the drive system's motor speed is controlled by varying the frequency and voltage of the applied Alternating Current (AC) supply. The system allows optimum frequency to produce the desired motion. The advantages of VVVF drive includes low starting current (about 1.8 x rated current); high power factor and efficiency; and good ride quality and floor leveling.

With Variable Voltage AC Drive (VVAC), the drive system's motor speed is controlled by varying the amplitude of the applied AC voltage. This form of control requires high current and causes a low power factor.

VVVF motors are more efficient than VVAC motors.

How do I nominate an efficiency measure for my lift?

Lift efficiency measures are not available in BASIX.

If you wish to install an efficiency measure, such as energy recovery back to grid, you will need to contact the lift manufacturer and the relevant energy utility when considering the option to feed energy back into the grid. To get the efficiency measure appropriately rewarded in BASIX, the proposed development will need to be assessed via the Alternative Assessment process.

Codes and Standards

 The Australian Standard SAA Lift Code AS 1735.

 

Alternative energy supply

An alternative energy system generates electricity using an energy source other than the electricity supply grid. This includes photovoltaic power systems and wind generators. The alternative energy system must be located on the same piece of land as the proposed development.

Central cooling systems

What is the most efficient central cooling system to install?

Generally, a well-designed central cooling system will provide greater efficiency than individual units, but efficiency and stability of operation of central systems can be compromised when only a small proportion of apartments are using air conditioning. A central system is unlikely to be practical for small developments of less than about 50 apartments.

In general, a central chilled water fan coil unit system using high efficiency water cooled chillers will be the most efficient central cooling system choice. Though common in hotels, it is not as common in residential design, due to the challenge of apportioning the energy cost between apartments. If a source of cogeneration heat is available, a central chilled water fan coil unit system with an absorption chiller would not only be energy efficient but would also have energy costs low enough that apportioning may not be an issue.

Gas-driven options have lower efficiency than their electric alternatives, but may actually score better due to the lower greenhouse potential of gas compared to electricity.

A central system using high efficiency water source packaged unit system has the advantage that the majority of the energy cost can be metered at the apartment. Depending on the climate, such systems may have efficiency better than an equivalent chilled water fan coil system, though high efficiency water source units are not readily available.

Low/medium efficiency systems will not score as well in BASIX as high efficiency options.

Systems using an evaporative process for heat rejection (cooling tower, evaporative fluid cooler or evaporative condenser) generally provide better efficiency than air cooled equipment, though not in all climates.

A low efficiency central water source packaged unit system provides better efficiency than a central fan coil unit system with medium efficiency air-cooled chillers, a central variable refrigerant volume unit system or individual unit system.

The sizing (and capital cost) of a central cooling system is very dependent upon the thermal performance of the building envelope – particularly reduction of solar gain. Smart building design and glazing techniques can cut capital costs of cooling equipment, while large areas of unprotected glass can lead to such high peak solar gains that either the local cooling capacity will be inadequate or capital costs will be high.

When choosing a cooling system, energy efficiency is one of many factors that should be considered. Apart from initial cost, other considerations include maintenance cost, health and safety issues, reliability, maintainability and life expectancy.

As with central hot water systems, effective insulation of chilled water or refrigerant pipes is also critical if high efficiency is to be achieved. The Building Code of Australia (BCA) requires minimum level of insulation for insulating of heating and cooling piping, vessels and tanks.

Central hot water

Central hot water system is a system that supplies hot water to more than one dwelling (generally all dwellings) from a central source.

BASIX recognises the following types of central hot water systems:

  • Co-generation system
  • Solar - gas boosted
  • Solar - electric boosted
  • Electric heat pump - gas boosted
  • Electric heat pump - air sourced
  • Gas instantaneous
  • Gas-fired boiler
  • Gas-fired storage (manifolded)
  • Electric instantaneous
  • Electric storage

It is highly recommended that the design and installation of a central hot water system is carried out in association with a qualified hydraulic consultant. They will help you with some of the information required for BASIX.

If a solar central hot water system is chosen then the solar collector area must also be entered into BASIX (larger collector areas collect more solar energy and therefore reduce the use of gas or electric boost).

The piping insulation on internal and external piping must also be entered into BASIX (Insulation level influences the amount of heat lost from the hot water and therefore the energy use of the hot water system). 

What is the most efficient central hot water system available?

A co-generation system, which produces power and usable heat to heat hot water, is the most efficient central hot water system to install. After this, centralised solar (gas boosted) and heat pump systems are the most efficient followed by solar (electric boosted) and high efficiency gas systems.

High losses can result from uninsulated or inadequately insulated hot water system pipes. Insulating the central system's ringmain and supply risers to a high level, such as R1.0 (approximately 38mm of insulation) will result in maximum greenhouse gas emission savings and an excellent hot water contribution to the BASIX energy score.

Solar collector area

The solar collector area is the flat panel area of the solar hot water system that is exposed to the sun.

For multi unit developments an approximate rule of thumb is that 0.5 – 1 flat plate panel (2m2) will usually be required per apartment.

Note: Solar collectors seem to have a smaller area when displayed in plan view, since they are typically installed at an angle to catch the sun, and not installed horizontally. The solar collector area entered in BASIX should be calculated based on the panel dimensions from the manufacturer, and not straight from the plans.

Contact your hot water system manufacturer for the best advice on sizing a large scale solar hot water system for your proposed development.

Co-generation

Using co-generation heat for central systems

Co-generation heat can be used for water heating, space heating, absorption chilling (Central cooling) and pool and spa heating.

Small co-generation systems 

A small capacity system (eg. 50 kW) could provide the entire hot water demand for a 200 apartment building, in addition to a small amount of electricity.

Heat rejection methods

BASIX recognises the following heat rejection methods for central cooling systems:

  • Cooling tower
  • Evaporative fluid cooler
  • Evaporative cooled condenser
  • Air cooled condenser

The available heat rejection methods depend on the type of system selected.

Energy sources for cooling systems

BASIX recognises the following energy sources for cooling systems:

  • co-generation heat / gas absorption (cooling by absorption chiller with all heat input derived from cogeneration heat sources, boosted by a gas-fired heat source when sufficient cogeneration heat is not available)
  • gas driven compressor
  • electric driven compressor

Note: The energy source options vary depending on the cooling system selected.

Building management systems

Applies to multi-dwelling developments only.

A Building Management System (BMS) is a system designed to control, monitor and optimise various building services, including lighting, heating, ventilation, cooling, swimming pool pumps and water use in cooling towers.

Optimising these services can result in energy savings. Most systems are computer-controlled and control services by either time (when is the service turned on / off) or other parameters such as temperature or light level.

Clothes drying (common areas)

In BASIX the installation of clothes lines reduces the energy use assigned to clothes dryers.

BASIX includes the option of installing a common area clothes drying line in multi-unit developments.

NCC requirements for common area clothes drying lines

Clothes drying facilities must be provided as part of the National Construction Code (See NCC volume 1: Part F2 Sanitary and other facilities).

Piping insulation

The piping insulation on internal and external piping must also be entered into BASIX. The insulation level influences the amount of heat lost from the hot water and therefore the energy use of the hot water system. The insulation options are:

  • No external/internal pipework
  • R1.0 (~38 mm)
  • R0.75 (~32 mm)
  • R0.6 (~25 mm)
  • R0.45 (~20 mm)
  • R0.3 (13 mm)

Piping insulation (ringmain and supply riser)

The National Construction Code specifies minimum piping insulation requirements for central hot water system pipes.

Insulation can be made from a closed cell polymer, nitrile, fibreglass or equivalent.

Insulation is applied to the central hot water system's ringmain and supply risers. Note that pipe connections should also be insulated.

For more detailed information on hot water system piping materials and thicknesses (R-values) contact your local piping insulation manufacturer.

Pipe sizing

Hot water pipe diameter and length is not currently assessed in BASIX, since design of these occurs after approval of the development application for the proposed development. It is still important to recognise their importance to good design.

Design the centralised hot water system at the early planning stages of a development to ensure adequate space within the building to position centralised hot water piping, its associated insulation and storage tanks.

Carry out the design of a central hot water system through a qualified hydraulic consultant briefed to aim for best practice.