Sizable energy-efficiency gains can usually be achieved in lighting and HVAC. Commercial appliances such as refrigeration, cooking and office equipment can also be upgraded with more energy-efficient models.
Lighting can account for up to 40% of total electricity use and energy cost in the commercial sector, depending on facility type. There are numerous low-cost and no-cost measures available to reduce lighting costs, such as removing unnecessary lighting and automatic control of lights. Combining such measures with the upgrading of lighting equipment can result in large savings in lighting costs.
Reduce the need for artificial lighting
- Use lighter colours for ceilings, walls, floors and furniture so that the light is reflected more effectively within the space.
- Improve 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 on and off manually or automatically, can often be implemented without 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, or with ‘plug and play’ linear light emitting diodes (LEDs) replacements which are now becoming cost-effective. Compact fluorescent lamps (CFLs) can also be replaced with LEDs.
LEDs can also provide greater amenity for occupants, and are considered safer as they don’t contain mercury as CFLs do. Reduction in the cost of LED lighting in recent years makes the business case for upgrades even stronger. Putting a timer or motion-sensing system in place will further increase savings.
Significant savings in HVAC energy use can be achieved through through clever design, building retrofits and installation of efficient equipment.
Reduce the need for heating and cooling
- 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 unwanted heat gain or loss through windows. Use curtains or blinds and window shading combined with double-glazing or low-emissivity windows.
Optimise existing HVAC systems
HVAC systems can usually be optimised by providing air-conditioning only when and where it is required.
Expand the temperature range settings for a comfortable environment where no heating or cooling is operating. Cooling requirements can be minimised through economy cycles, opening windows for natural ventilation and user-controlled local environments (e.g. small fans) which enable a larger comfort range and a reduction in air-conditioning loads.
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 intervals when 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 up to 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 by:
- 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
The efficiency of modern HVAC equipment has improved substantially in recent years, and simple replacement upgrades can lead to energy savings of 30% or more. Applying demand management and HVAC optimisation steps can also 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 and contribute to unwanted heat build up.
Ensure new electronics purchases, such as photocopiers, laptops and computer systems, are the best performers in their category in relation to energy usage.
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. In 2017 the Council of Australian Governments (COAG) energy ministers agreed to increase Australasian minimum energy performance standards (MEPS) levels for refrigerated display cabinets.
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.
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
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
- rearranging rack layout
- optimising air conditioner temperatures to suit newer equipment
Co-generation (co-gen) and tri-generation (tri-gen) systems are onsite power generating engines which harness waste heat, greatly improving the efficiency of energy use in power generation. Another advantage is that generating electricity locally avoids transmission and distribution network losses.
Co-gen systems produce electrical power while capturing and utilising the heat that arises as a by-product of the process. Tri-gen uses some of the remaining lower grade heat to drive cooling systems as well as capturing heat from the initial power generation. Systems can reduce energy demand and greenhouse gas emissions by as much as 20–30% and provide a return on investment when effectively implemented.
Both co-gen and tri-gen 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.
Tri-gen 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 co-gen.
Reflective cool roofs are achieved by painting surfaces with special coatings or by applying a covering material. This can reflect solar radiation by up to 85%, reducing heat transfer, and can be cost-effective in decreasing cooling costs in some situations.
Cool roof suitability depends on a number of factors, especially the local climate and building type. Areas with long hot summers and mild (or no) winters are generally the most suitable for cool roofs. Low-rise buildings with expansive metal roofs are especially exposed to solar radiation and may benefit the most from cool roofs.
A solar PV array also helps keep the roof cool, and can be used as a cool roof design.
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, especially where large amounts of concrete and steel are used. 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.
An Australian innovation in air-conditioning systems is the development of hybrid dry air/water cooling systems, which use 80% less water than the typical water-based cooling towers. This also significantly reduces the life cycle energy consumption associated with water use, such as the treatment and pumping of freshwater from water storages to buildings.