Air Conditioning

Discussion

Growing demand for air conditioning, especially for residential use, is increasing overall electricity consumption, and putting strain on existing electricity transmission and generation infrastructure, which cannot cope with demand spikes on the hottest days of the year.

How to reduce overall demand.

Overall demand can be reduced by enabling houses and other buildings to keep within a comfortable temperature range without (or with minimal need for) air conditioning on even the hottest days. And by preferring air conditioning systems that use less electricity to deliver the same amount of coolness.

How to reduce peak demand.

To keep peak power use within the capacity of infrastructure, power users can be enouraged to shift demand from peak to non-periods.

A building could be air-conditioned to coolness during the offpeak period, then the airconditioning turned off during the peak, with the coolness maintained by good insulation.

But this may increase overall demand. Contrast the efficiency of pulling enough coolness out of cooler night air to last throughout the hot day, with pulling coolness out of warmer day air only when needed.

Articles

Household Air Conditioners - How to Reduce Their Incidence and Use. Michael Robertson, Urban Ecology Australia, 2005.2

Increasing use of air conditioners in Australian cities is putting strain on local electricity transmission infrastructure and is adding to greenhouse gas emission from fossil-fuel powered electricity generators.

Readings

Small Business Air Conditioning

Source: Air Conditioning. Sustainable Victoria

Air conditioning controls the temperature, humidity, ventilation and cleanliness of air in an enclosed area. Cooling usually accounts for around 10% of a typical small business' energy bills. Efficient air conditioning saves money and makes the working environment more comfortable and productive.

Air Conditioning and Electricity Transmission

Source: ERAA submission to Productivity Commission Inquiry on Energy Efficiency (PDF) Energy Retailers Association of Australia, 2004.11

Air Conditioning on peak days is overloading the electricity transmission network.

1. Air conditioning is putting transmission networks under increasing stress in peak periods. Huge amounts of capital need to be spent (not invested) to accommodate very small number of days per year.

2. These network charges (some States have increased the network charges recently) directly impact large business consumers of energy.

3. [Residential] Consumers with air-conditioning do not pay for the full cost of the energy and therefore there is no incentive to change their behaviour.

4. [Residential] Consumers who do not have air-conditioning are cross subsidizing consumers who do have air-conditioning.

5. Green house gas emissions continue to grow (because of the extra generation needed for peak times) as there are no clear signals to consumers to change behaviour.

Managing Demand from Small Air Conditioners

Source: A National Demand Management Strategy for Small Airconditioners. Energy Rating.

Air conditioner peak demand is one of the major factors driving capital investment in the National Electricity Market, as well as a mechanism for cross-subsidy between AC users and non-users. If no action is taken, both energy and peak demand are projected to increase rapidly in the coming years.

This paper reviews a range of measures potentially impacting on the energy use and contribution to summer day peak demand of domestic and small business air conditioning in Australia.

Household Air Conditioning Demand

Source: We're past our peak. Mike Hanley, CFO, 1 December 2004.

Tired of blackouts? Blame the air-conditioning in your car.

Hectares of housing estates containing large, two-storey dwellings of 300-400 square metres, most sold off the plan with air-conditioning included, mean that on hot days peak loads on the country's power infrastructure reach unprecedented levels.

"The big mistake was putting air-conditioning in cars." If people were not used to being cool in their vehicles, they would not demand it in their homes. (Tony O'Dwyer, National Economics)

Overall growth in power demand over the past 10 years was 2.5% a year on average, but over the past year it increased to 3.3%. Residential demand grew 3.6%, and business demand by 2.5%, over the past 12 months. (Energy Supply Association of Australia)

Peak power attracts substantial price hikes on the National Electricity Market; on a number of summer days last year the price reached $10,000 per megawatt hour (MWh), compared with average period prices of under $50/MWh.

Generators have to "provide the capacity to power the last air-conditioner on the hottest day, but that capacity is used for, perhaps, 24 hours each year." (Roman Domanski, Energy Users Association of Australia). The ESAA claims that it will need $20 billion of investment in energy infrastructure by 2020.

Demand management - providing power users with the ability to monitor power prices and change usage accordingly - might be a long-term way around the country's infrastructure issues. (O'Dwyer)

Evidence suggests that, where such capability does exist, it is effective. Customers are generally willing to change their behavior when prices reach about $1000/MWh. (EUAA)

The country's first demand facility operator, Energy Response, opens for business this summer.

School Air Conditioning Demand

Source: Schools Losing Their Cool in Battle for Air-conditioning. Amy Laws, Sydney Morning Herald, 2005.2.6

With temperatures expected to hit 35 degrees in Sydney's west on Tuesday, parents have stepped up their campaign to have air-conditioning installed in more of the state's permanent classrooms.

"There would be many members of the community who would say 'we did it like that when we were at school, get over it', but ... I think we need to move with the times, especially in a climate like ours," said Parents and Citizens Association president Sharryn Brownlee.

Encouraging Demand-Side Response to Electricity Price Fluctuations

Source: Demand-Side Response and the Electricity Network. CSIRO

The Australian National Electricity Market is characterised by a paradigm where electricity suppliers set the price of electricity and electricity consumers accept the price without altering consumption behaviour. There is very little demand-side response.

Lack of response is perhaps understandable because there is currently limited ability for electricity to be stored economically and there is only limited ability to obtain forward estimates of electricity price. Consequently, consumers must use the electricity as soon as it is purchased and they have very little time to respond to price fluctuations. Even worse, the cost of electricity for most consumers is a relatively small fraction of their operating costs, so very few electricity consumers bother to manage their electricity consumption.

There are a large variety of physical assets and applications that can be switched on or off to achieve a reduction in electricity demand from the electricity network. In addition to these physical assets there are a number of management systems available for controlling and automating the switching of these assets. Some common demand side response opportunities are listed.

A demand side aggregator would provide an interface between customers and power utilities. It would have an extensive list of customers registered to provide load shedding or activate distributed generation when required, and could sell this capability to whichever power utility required load shedding or peaking generation at a given time.

Reducing Air Conditioning Demand

Source: Consumer Guide For Air Conditioners. Cool Communities in SA, CCSA.

In South Australia, the growth in sales of air conditioners - particularly reverse cycle air conditioners - has seen a dramatic increases in the demand for electricity on hot summer days and the need to build costly power stations to meet this demand. Choosing the most energy efficienct form of heating and cooling can make a big difference to reducing energy use, greenhouse gas emissions and the need to build more polluting power stations.

A well designed energy efficienct home can be comfortable to live in with little (or even no ) heating or cooling. For example, in a well designed home, ceiling fans may be sufficienct for summer.

If you are considering an airconditioner it is important to consider not only its upfront costs but also the running costs (and associated greenhouse gases). This article provides information on the two main types of air conditioners - evaporative and reverse cycle.

Air Conditioning Demand Due to Other Appliances

Source: Air Conditioning. Wikipedia.

To remove heat from a building, an air conditioner must increase its electricity consumption in proportion to the energy to be removed, and in inverse proportion to its efficiency in doing so. To remove the heat generated by a 100 Watt light bulb, and air conditioner with an efficiency of 50% must draw 200 Watts (total power draw: 300 Watts).

Technologies for Demand Reduction and Demand Shifting

Source: Efficient Energy Use - Refrigeration and Air Conditioning. CSIRO

New control technologies can be used both to reduce electricity consumption and to shift electricity consumption away from periods of peak demand. Peak demand management will allow electricity network service providers to defer capital expenditure on network augmentation in constrained localities.

The transcritical CO2 heatpump is a new technology, developed overseas, that can simultaneously provide refrigeration at temperatures below 0°C and utilise the waste heat to obtain relatively high temperature hot water at temperatures up to 90°C. This can reduce greenhouse gas emissions by about 25% compared with conventional separate heating and refrigeration systems.

Technology for storing cold that has been produced overnight (eg ice storage, chilled water storage etc) can be used to shift electricity consumption away from periods of peak demand.

Technologies to convert waste heat from prime movers (e.g. gas engines, gas turbines or fuel cells) into cooling or building dehumidification can reduce peak summer electricity consumption and reduce greenhouse gas emissions from air-conditioning by about 25%.

2007.3.26