Ways to save – Commercial buildings
The commercial buildings sector is on the cutting-edge of energy-efficiency innovation, with numerous innovations invigorating the industry.
Ways to save
Sizable energy-efficiency reductions can be achieved in lighting and HVAC. Commercial appliances such as refrigeration, cooking and office equipment can also be upgraded with more energy-efficient models.
Improve lighting efficiency
Lighting can account for up to 40% of energy costs in the commercial buildings. There are many low-cost and no-cost measures available to reduce lighting costs. Combining such measures with the upgrading of lighting equipment can result in significant savings in lighting costs.
Reduce the need for artificial lighting
- using lighter colours for ceilings, walls, floors and furniture so that the light is reflected more effectively within the space
- improving natural daylighting through building design or retrofitting
- rearrange rooms to achieve the most effective lighting conditions.
Optimise the use of existing lighting systems
Traditionally, commercial building lighting systems have been designed to provide a uniform task lighting level over the whole office space. This can result in as much as 85% excess illumination. Task-appropriate lighting can save significant amounts of energy.
Many lighting efficiency opportunities, such as turning lights off manually or automatically when not needed, can also be implemented without any capital outlay or redesigning of lighting systems.
Upgrade lighting systems
There are excellent opportunities for energy savings whenever upgrades or refurbishments are planned. For instance, it is possible to replace inefficient T12 or T8 fluorescent bulbs with new super T8 and T5 fluorescent bulbs, and to replace CFLs with LEDs. Putting a timer or motion-sensing system in place will further increase savings.
Improve HVAC efficiency
Significant savings can be made when constructing a new building through clever design and installation of efficient equipment.
- Insulate walls and ceiling.
- Reduce heat generation from lighting by upgrading to LED.
- Design spaces that can be closed off to minimise heating and cooling needs.
- Avoid losses through windows. Use curtains or blinds combined with double-glazing or low-emissivity windows.
- Expand the temperature gap to at least 19–25ºC for a comfortable environment where no heating or cooling is operating. Cooling requirements can be minimised through economy cycles, opening windows and user-controlled local environments (e.g. use of small fans or local controls) which enable a larger comfort range and a reduction in air-conditioning loads.
Optimise existing HVAC systems
Existing HVAC systems can usually be optimised by providing air-conditioning only when and where it is required. For example:
- Operating times of HVAC control systems can normally be reduced by at least 10% with negligible impact on comfort by using the building’s thermal mass to maintain a relatively similar air temperature for a period of time. Units can be cycled off and on for periods of time while only the circulation fans are on. Delaying the start time of HVAC systems each morning can also minimise energy usage.
- Ventilation systems can be optimised by using high efficiency fans and motors, demand-controlled ventilation and by isolating fan motors and other heat-generating components from the supply airstream.
- Variable speed drives (VSDs) on air-conditioning fans enable the speed of fan motors to be controlled to match the amount of air required to be moved through the building. VSDs can save 30–40% on the investment annually.
- Air distribution systems can be optimised and streamlined, where possible, through good ductwork design to reduce air resistance. Poor distribution system and ductwork design can reduce supply flow-rate and air-conditioning efficiency by as much as 10%.
Ensure good maintenance practices
Proper maintenance can save up to 10% of space air-conditioning energy usage through measures such as:
- cleaning distribution systems (fans, filters and air ducts) quarterly
- maintaining and regularly tuning all HVAC equipment and sensors.
Upgrade or replace with more energy efficient HVAC systems
Applying demand management and HVAC optimisation steps can lead to significant cost savings by enabling a downsizing of existing HVAC systems. Downsizing HVAC systems can also lead to significant co-benefits such as increased water savings, as HVAC systems are responsible for up to 30% of water use in commercial buildings.
When it comes time to upgrade HVAC systems, different approaches such as radiant chilled-ceiling cooling and displacement ventilation can further assist to achieve significant reductions in mechanical HVAC requirements.
Upgrade computers and other electronic office equipment
Significant energy efficiency savings can be achieved through upgrading and retrofitting computers and other electronic equipment as these can contribute up to 30% of an office’s energy use.
Ensure new electronics purchases, such as televisions, electronic menus, laptops and computer systems, are the best performers in their category in relation to energy usage.
The Energy Rating website provides information on the energy performance of a range of residential, office and industrial equipment which is communicated via energy rating labels.
The website also includes information on mandatory minimum energy performance standards (MEPS) which apply to a large range of equipment, appliances and lighting products including refrigerators, clothes washers, televisions, compact fluorescent lamps and industrial motors.Equipment Energy Efficiency (E3) program
E3 is a cross-jurisdictional program through which the Australian Government, the state and territory governments, and the New Zealand Government, collaborate to deliver a single program on energy-efficiency standards and labelling for equipment and appliances.
Upgrade commercial refrigeration equipment
Commercial refrigeration is a substantial energy user, yet often little consideration is given to its energy efficiency, operating costs or environmental impact. The energy costs of refrigeration plant can be reduced by around 40% through adoption of best energy efficient equipment and techniques.
Supermarkets and other food retailers often have open refrigeration units for ease of customer access. Enclosing refrigeration units with glass doors, which customers can easily open, can reduce refrigeration loads.
A technology guide produced by the NSW Government outlines 15 energy-saving technologies which can contribute to more energy-efficient commercial refrigeration. While many of these measures require capital outlays, case studies indicate the payback period is often less than three years.
Upgrade cooking equipment
There is significant room to improve the design and energy efficiency of ovens. Commercial ovens are usually made by smaller scale manufacturers and due to the low volume of ovens manufactured, tend not to go through the same rigorous design processes as domestic appliances.
When upgrading commercial ovens, look for the following features to ensure the oven is as efficient as possible:
- fully insulated solid doors and no glass
- good seals on all four sides of oven doors to reduce heat loss
- no metal joints that provide a thermal bridge from the inside to the outside, allowing heat loss
- exhaust hoods designed to reduce electricity consumption and increase amount of heat recovered by the system
Improve the energy efficiency of data centres
The use of data centre services is growing as businesses expand their array of digital hardware resources, procure larger servers and increase their online services. Office computers, servers and data centres can use up to 40% of the energy in commercial office buildings.
Some of the main strategies include:
- reducing power consumption with virtualisation
- improving airflow
- properly decommissioning redundant servers
- upgrading to more efficient equipment
- consolidating and optimising storage
- using fresh air for cooling.
Cogeneration or trigeneration technologies
Cogeneration (cogen) and trigeneration (trigen) systems harness 'excess' heat, greatly improving the efficiency of energy use in power generation. Another advantage is generating electricity locally avoids transmission and distribution network losses.
Cogen systems produce electrical power while capturing and utilising the heat that arises as a by-product of the process. Trigen uses some of the remaining lower grade heat for cooling as well as capturing heat from the initial power generation. Systems typically have returns on investment in the range of 5–20% and can reduce energy demand and greenhouse gas emissions by as much as 20–30%.
Both cogen and trigen systems are appropriate to use at sites that have high demand for heating, such as hotels, hospitals, industrial laundries, data centres and swimming pools. They are especially cost effective when heating and/or cooling demands are present throughout the year.
Trigen can be cost-effective in facilities such as large data centres, which require onsite electricity generation and have substantial year-round cooling requirements. In these cases, heat by-product can be used for cooling in an absorption chiller.
Developments in small-scale technologies such as microturbines and fuel cells are also opening up new opportunities for the application of cogen.
Reflective cool roofs are achieved by painting surfaces with a white (or light-coloured) coating or by applying a covering material. This can reflect solar radiation by up to 85%, reducing heat transfer and can be a cost-effective in decreasing cooling in commercial buildings.
Cool roof suitability depends on a number of factors, especially the local climate. Areas with a long hot summer and mild (or no) winters are generally the most suitable for cool roofs.
Consider combining a 'cool roof' with solar panel (or solar tile) placement.
Low embodied-energy materials
The concept of embodied energy has started to be included in life cycle energy calculations of buildings.
The average commercial building contains tens of thousands of gigajoules of energy embodied in its construction materials. Databases such as the EcoSpecifier can assist in selecting innovative materials with low embodied energies.
Recycling building materials can reduce capital costs for new buildings.
Water-energy nexus efficiency opportunities
Australian innovations in air-conditioning systems, known as hybrid dry air/water cooling systems, use 80% less water than the typical water-based cooling towers, while only using 5–10% more energy. This also significantly reduces the life cycle energy consumption associated with water use, such as the treatment and pumping of freshwater from dams to buildings.
- ClimateWorks Australia (2010)
- ClimateWorks Australia (2010) Commercial Buildings Emission Reduction Opportunities. ClimateWorks Australia and Carbon Trust Australia (Opens in a new window) PDF 1.0 MB