AS5389 Solar Air-conditioning Australian

Transcription

1 AS5389 Solar Air-conditioning Australian Standard Overview of development Mark Goldsworthy, CSIRO ENERGY TECHNOLOGY Australian Solar Cooling Interest Group Conference 2013, 12 th April Sydney 1 Overview A Solar Air-conditioning Australian Standard is being developed Why? (background information) What are the challenges? What approach has been taken? What stage are we up to? 2 AS5389 Solar air-conditioning standard development Mark Goldsworthy 2

2 Background National Electricity Market in Australia Australia does not have cheap electricity despite our reliance on coal Retail cost expected to increase by 37% from % increase due to transmission & distribution, 31% green schemes Total consumption decreased from Peak consumption forecast to increase sharply Figures taken from: Green Energy Markets, 2012 Impact of market based measures on NEM power consumption. Hawthorn. 3 AS5389 Solar air-conditioning standard development Mark Goldsworthy 3 Background what can we do? Reduce peak demand by: Making the price of electricity reflect the cost (time of use tariff) Provide incentives for technology which reduces peak demand In Australia, air-conditioning causes peak demand Solar cooling and heating can reduce summer and winter peaks BUT: How do we know if a system really saves energy? How do we provide an incentive which is fair (i.e. cost effective)? 4 AS5389 Solar air-conditioning standard development Mark Goldsworthy 4

3 Background what can we do? Reduce peak demand by: Making the price of electricity reflect the cost (time of use tariff) Provide incentives for technology which reduces peak demand In Australia, air-conditioning causes peak demand Solar cooling and heating can reduce summer and winter peaks BUT: How do we know if a system really saves energy? How do we provide an incentive which is fair (i.e. cost effective)? 5 AS5389 Solar air-conditioning standard development Mark Goldsworthy 5 Background Australian solar hot water rebate Solar hot water system deemed energy savings estimated using CTSS method Rebate based on estimated energy saving 1. Test components (e.g. hot water tank, collector) at selected conditions 2. Calibrate component models 3. Assume a typical hot water usage pattern & climate 4. Run an annual simulation to estimate energy consumption 5. Define a reference energy consumption 6. Calculate energy savings RECs/STCs 7. Provide a conversion from energy saving to dollar saving 8. Consumer offered a cash rebate CTSS method in Australian Standard (AS4234) market mechanism Is it working? CTSS -> Component Testing System Simulation 6 AS5389 Solar air-conditioning standard development Mark Goldsworthy 6

4 Background solar hot water systems Rebate saves ~20% of purchase cost 1,500,000 systems installed under MRET (10% of houses) Reduced consumption by 1,300 GWh/annum (3% of 2020 target) g (%) Share of solar water heating Invention Share of solar heaters Elec price index R&D programs Fed government installs systems in NT AS1056 AS4234 MEPS (electric) VIC rebate MRET SA rebate NSW rebate WArebate Fedrebate ed to CPI) Retail electricty price index (scale Comparison of percentage of solar water heaters installed in residential buildings 7 AS5389 Solar air-conditioning standard development Mark Goldsworthy 7 Challenges for a solar air-conditioning standard Potential designs diverse and/or complex Performance dependent on many inputs (expensive testing) Air-conditioner usage patterns highly variable Building construction has large influence standard isation Solar hot water systems may be coupled AS4234 climates zones not suitable for air-conditioning (too coarse) consistency with existing standards Not everyone has an air-conditioner reference? Some systems won t work without sun Is gas usage better than electricity (emissions?) Potential changes to user behaviour ( solar label)? defining a meaningful saving 8 AS5389 Solar air-conditioning standard development Mark Goldsworthy 8

5 Approach overview- standardisation Treat solar air-conditioner as black box for testing & modelling Use generic model coupled with limited test points Indicative (average) house model and usage pattern (to be updated) 9 AS5389 Solar air-conditioning standard development Mark Goldsworthy 9 Approach overview- consistency with existing standards Hot water demand (in AS4234) must be satisfied at all times (i.e. preference to hot water) System components (e.g. collector, storage tank) tested according to Aust. Standards New climate zones overlay existing hot water climate zones Climate zones for space cooling and heating 10 AS5389 Solar air-conditioning standard development Mark Goldsworthy 10

6 Approach overview- defining the reference Reference system energy use is for an equivalent function i.e. the same amount of cooling/heating Reference system either vapour compression a/c, heat pump or gas Efficiency is current MEPS value (AEER=3.1). Overall building load may be scaled to match solar system capacity Minimum comfort conditions must be maintained 95% of the conditioned time Autonomous systems can use a default backup a/c to meet the comfort but: annual energy saving must be >60%. 11 AS5389 Solar air-conditioning standard development Mark Goldsworthy 11 Approach overview Standard currently applies to: - i) Desiccant wheel based air-conditioners ii) Solar space heaters which use a fan-coil Aim is to expand the method to other components e.g. adsorption and adsorption chillers Calculates displaced energy & specific GHG 12 AS5389 Solar air-conditioning standard development Mark Goldsworthy 12

7 Approach detail generic desiccant air-conditioner Modified ASHRAE174 laboratory test procedure 9 inputs simplified to 5 variables, 1 fixed & 3 mode specific parameters Equipment performance divided into operating modes Characterisation in terms of output conditions (not cooling capacity) Inputs and outputs for generic black-box desiccant air-conditioner model 13 AS5389 Solar air-conditioning standard development Mark Goldsworthy 13 Generic desiccant air-conditioner model validation 1 Comparison of generic model with 30 test points versus exact performance 5 different desiccant air-conditioner designs 400 sets of conditions chosen randomly RMS deviation of outlet values compared Ts within ±1 C, HRs within ±0.5g/kg, Tw within ±2 C 3 of the air conditioner designs tested 14 AS5389 Solar air-conditioning standard development Mark Goldsworthy 14

8 Generic desiccant air-conditioner model validation 2 Annual simulations Assumed building, internal loads, occupancy & usage patterns, weather data Comparison of calibrated generic interpolation method with exact result for 5 systems Total predicted cooling within 10% of exact model Acceptable for estimating typical savings given; Variability in usage, building envelope, installation quality, climate etc Ambiguity in reference system definition Provided; Average saving across all installations is accurate No systematic bias between systems Comparison of annual predicted cooling, exact and generic models 15 AS5389 Solar air-conditioning standard development Mark Goldsworthy 15 Where to from here? AS5389 Solar cooling and heating systems Calculation of energy consumption o released as provisional standard 2013 o 2 years of public comment o then accept/reject/modified 2015 Other technologies (e.g. ad/absorption) need to be included Needs validation, case studies & industry feedback Must be enacted by legislation for real impact o AS4234 released in 1994, enacted (MRET) AS5389 Solar air-conditioning standard development Mark Goldsworthy 16

9 Standards Australia CS-28 Committee: Thank you Energy Technology/Solar Cooling Dr Mark Goldsworthy Research Engineer t e mark.goldsworthy@csiro.au w ENERGY TECHNOLOGY 17