Evaporative coolers as a substitute for air conditioning?

1. Evaporative coolers as a substitute for air conditioning? Graham PalmerM.Eng (Sustainable Energy) RMITIEST5011Feb 2008

2. Air conditioning versus evaporative cooling • Refrigerated - wall units, split systems, ducted • Market dominated by wall hung splits sold by bulk stores • Rapidly increasing a/c penetration – Australian sales of 800,000 units per annum (AGO 2006) • Air conditioners have dropped in price and been aggressively marketed • COP of 2.0 to 4.1 – current MEPS require 2.75 • A/C efficiency drops as temperature rises Air conditioning • Ducted • Main market is now new homes • Falling market share overall • COP of typically 14 - star rating doesn’t apply, but would be 41! • Efficiency increases as temperature rises • Performance drops as humidity rises Evaporative coolers

3. What’s wrong with air conditioners? • Top 10% of network capacity used 1% of the time • Problem mainly caused by residential air conditioning on hot days • Cooling only represents small component (~2%) of residential greenhouse emissions but aggravates electricity supply policy debate • Authorities engaged in problem of “keeping the lights on” • Demand growth out of control • $13,000 per air conditioner potentially (Qld Minister for Energy 2004) • Requires additional peaking plant + transmission • A/C cost $300-$500 per 1 kW of electrical power • Estimated cost of $2,800 to provide an additional 1 kW of power (BCSE 2003) • Yet same a/c may produce revenues of $12/annum • Householders without a/c are effectively subsidising those with a/c Source: Watt 2005

4. Evaporative coolers • Principle dates back to ancient Egypt • Use approx 1/5 to 1/4 of the energy where conditions are appropriate • Third of the capital cost compared to ducted refrigerated air conditioning • Whole house evap. similar to two splits • Consumers report very high satisfaction with coolers (Melbourne) – prefer evaporative to refrigerated regardless of costs • Typical cost $3500 - $4500 for whole house • Water use an issue, but typically < 3% of total annual usage city areas, but >10% rural Qld • Relative performance improves with temperature for a given absolute humidity • Ineffective on humid days, but ventilation improves comfort, particularly with ceiling fans Source : http://www.brivis.com.au

5. Evaporative cooler penetration • Maintaining market share in new homes in Vic. but declining for existing homes • Australian sales approx. 55,000 units per annum compared to 800,000 refrigerated • Market share 8% • Main suppliers Bonaire, Breezair, Brivis

6. Why aren’t evaporative coolers more popular? • Refrigerated wall splits getting cheaper because of reduction in manufacturing costs and strong Aussie dollar • Virtually all the marketing is by large Japanese and Korean manufacturers • Require in-home quotation and experienced staff • Not suited to bulk store sales model • Walk out with a box • Split systems easier to install and preferred by many tradesmen • No thermostat – doesn’t match common expectations of operation • Some experts in the a/c trade prefer refrigerated • Margins squeezed on evaps - tradesmen can charge full rate on splits • Some old myths, stories and biases - “damp”, “swamp” etc.. • Depending on location, there may be a couple of days a year when they are not effective • Expectation of comfort changing, city higher than country – expect 22o all year round • Mostly Australian made, but manufacturers are now marketing refrigerated as well - has reduced possibility of industry wide promotion opportunities

7. Blue lined areas have potential for evaporative cooling. Region around NSW central coast and Sydney is marginal. Source : http://www.bom.gov.au/cgi-bin/climate/cgi_bin_scripts/clim_classification.cgi

8. MelbourneHourly temperature and RH for 1/1/2000 to 31/12/2000 100 80 Marginal 60 Good Relative humidity (%) 40 Ideal 20 0 5 10 15 20 25 30 35 40 45 Temperature (oC)

9. Melbourne & SydneyHourly temperature and RH for 1/1/2000 to 31/12/2000 100 Ineffective 80 Marginal 60 Good Relative humidity (%) 40 Ideal 20 0 5 10 15 20 25 30 35 40 45 Temperature (oC)

10. Overview • Evaporative coolers offer excellent performance in many regions in Australia in terms of comfort and energy consumption • Water an issue, but relatively minor and solvable • Not suitable in tropical/semi-tropical regions • Substantially better for greenhouse/peak demand • But many factors work against evaporative coolers • Low hanging fruit from a greenhouse viewpoint • Market share well below potential • Effective response to electricity network market failure

11. What should we do? • Evaps substantially reduce capital expenditures compared to air conditioners – why not provide incentives to purchasers through electricity retailers or government agencies? • Consumers not fully educated in choices, and the system works against effective information delivery – need govt. sponsored information • Straightforward, accessible information • Develop a simple measure of the performance of evaporative cooling for specific locations throughout Australia • Star rating • Smart metering and demand management • Encourage efficient technologies, including indirect evaporative for humid conditions

12. Highly effective Make PV mandatory with A/C Ban air conditioning Medium term greenhouse reduction potential Encourage evaporative cooling Remote demand control Time-of-day tariffs Lift MEPS Overall increase in electricity price Beneficial Existing home building standards Preferred policy New home building standards Less effective policy Irrelevant Easy Challenging Impossible Current Australian political feasibility

13. Thank you