Air Con and Refrigeration Efficiency in the Built Environment 1

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Tuesday, February 24th, 2015
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There are major energy savings available from air conditioning and refrigeration (HVACR) in Australia, in the order of $10 billion per year.

Accessing these savings requires significant changes in the way we design and manage for HVACR energy efficiency in all uses of HVACR and across the entire built environment; residential, commercial, industrial.

HVACR is of course pervasive:

  • There are about 53 million individual HVACR installations in Australia, worth about $100 billion in current dollars[1]
  • They consume at least 23 per cent of the electricity we generate ($14 billion per annum) [2]
  • They generate 12 to 14 per cent of national greenhouse gas (GHG) emissions[3]

Whilst a good deal of work has gone into making new buildings energy efficient (GBCA, NABERS), it is clear that a proportionate effort has not been made to address the existing building stock. At the same time the technology impacting HVACR energy efficiency is changing rapidly. The leading rating systems have yet to recognise the importance of embracing the full range of opportunities to optimise outcomes from an HVACR energy efficiency and emissions reduction point of view.

Despite the fact that HVACR is a primary source of energy consumption and GHG emissions, it is far from clear that enough attention is paid to HVACR energy efficiency.

Reports to Consider

The Australian Built Environment Council (ASBEC) and Climate Works have reported on energy efficiency opportunities in the built environment. The Second Plank produced by ASBEC in 2007 and the follow up report by the Allen Consulting Group in 2013, Energy Efficiency Measures In The Buildings Sector, examined energy efficiency in the built environment. Both reports list a series of ways to reduce energy consumption in residential and commercial buildings. Most of the proposed solutions directly or indirectly address HVACR.

Climate Works produced a similar list and quantified the potential gain by solution in their report, How to Increase Energy Efficiency in the Built Environment. There are many international studies that draw similar conclusions.

Despite this and considerable further reporting on the importance of HVACR energy consumption and the solutions, we don’t see HVACR energy efficiency being addressed comprehensively and systemically.

A recent report by Pitt & Sherry in association with Swinburne University (National Energy Efficient Building Project) raises fundamental questions about the all levels in the delivery of energy efficiency in the building industry.

“…Stakeholders also raised a very large number of concerns about the effectiveness of current energy performance requirements in the Code and their implementation. These concerns appear systemic in nature, in that they cover all aspects of the building supply chain and regulatory process and all building types,” the report reads.

“Many stakeholders believe that Code compliance is poor and, further, that Australia’s building energy performance falls a long way short of best practice. This implies higher energy use, higher emissions and higher overall costs for building owners and occupants.”

We strongly recommend that all have a good look at the report. It provides an excellent summary of the many factors that give rise to low energy efficiency in the built environment. The issues reported, of course, have a direct impact on HVACR energy efficiency.  These issues are reflected in the solutions we recommend.

The ARA has proposed that HVACR energy efficiency should be given higher priority and addressed as an integrated system. HVACR energy efficiency, in our view, is a function of:

  1. The measurement and remote management of energy consumption by source.
  2. Heat load reduction, being all of the technologies that reduce the heat load (or employ the heat load) in a building like air leakage, lighting, windows, reflective surfaces.
  3. Efficient vapour compression systems, being the mechanical devices that generate heating, cooling and refrigeration including fans and pumps that are central to vapor compression system efficiency.
  4. Ensuring all parties that can influence decision making across this range of factors are fully informed about the options and potential for improvement.

These factors need to be measured and managed as an integrated system for temperature control regardless of whether the objective is comfort or refrigerated goods production and distribution systems. We refer to the systemic solution as Integrated HVACR Energy Efficiency Engineering.

Measuring and Managing HVACR Energy Consumption

We start with the need to measure, remotely report and manage energy consumption by source because of the truism: “if you don’t measure it you can’t manage it,” and the corollary if you don’t measure the energy consumption of each appliance or device that generates heating and cooling individually, you can’t assess or manage the opportunity for improvement.

It is clear that this field is rapidly changing such that disaggregated and remote reporting of energy consumption will restructure the HVACR industry. If your HVACR contractor is not performing this function for you and using the new technologies that make it possible, you should find an energy savings consultant or facilities management supplier that is and can. By knowing and experimenting with ways to reduce energy consumption, we are confident that most HVACR users will find major opportunities to reduce energy consumption and cost.

New energy measurement and reporting technology like Watt Watchers enables the building owner to precisely measure energy consumption for every individual appliance over short time frames. This enables the energy user to know precisely which device is consuming energy and how much at short, discreet intervals. From there, building managers can experiment with the full array of ways to both reduce HVACR energy consumption and access energy under preferential terms.

The full range of methods for reducing the demand for temperature change and measuring HVACR performance can be considered using this data. Clearly, the energy consumption of vapour compression systems is central, but the opportunities to reduce the work required of these systems can also be examined, tested and optimised. We describe these opportunities below in the section titled Heat Load Management. Building management systems are a key element of energy measurement and control that can reduce HVACR energy use.

Maintenance is frequently overlooked as a source of HVACR energy efficiency. New energy management systems enable both the identification of maintenance needs and even the prediction of maintenance needs. They also enable predictive temperature control requirements that enable HVACR management that reflect predicted ambient weather conditions.

All of these opportunities and many more are made apparent and available by new energy management technology. So we suggest you measure it and manage HVACR for energy efficiency.

Heat Load Management

Heating and cooling obviously operates in the context of the ambient conditions within and surrounding a building. These can be reduced dramatically by employing the many solutions to control heat ingress or heat release. Window shading and double-glazed windows are an obvious solution and yet most windows in Australia are not double-glazed and replacing the entire window and frame is expensive. Retrofit double-glazing and reflective window films and blinds can achieve as much as a complete window replacement at a fraction of the cost. These can also be designed to deliver a range of comfort factors through differential treatments for various windows as they impact the occupants of the building.

There are many other solutions that can reduce the heat load of a building. Low heat lighting, reflective roofs and walls, and energy efficient fans and pumps are but some examples. Small adjustments to refrigeration and HVAC infrastructure like heat leakage and air flow adjustments should be optimised in concert with vapor compression system design.  Better ambient temperature management in a building can reduce refrigeration cost.

It is therefore important that the energy savings consultant or HVACR contractor take these factors into consideration when recommending energy savings investments. Conversely, it is simply wrong to design an HVACR system without optimising the heat load management systems in the building.

Vapour Compression

The vast majority of HVACR systems in use in Australia today are technologies that are energy inefficient because of a range of factors. The engineering of the industry has changed and continues to change at a rapid pace. Whilst it is difficult for HVACR contractors to keep up, the fact is that new vapour compression technology can reduce the energy cost of the built environment by a great deal. The opportunities include variable speed drives and inverter technologies as well as energy efficient refrigerants that in combination deliver over 50 per cent energy savings in and of themselves regardless of the factors listed above.

In the refrigerants field, we are forecasting rapid deployment of low Global Warming Potential (GWP) refrigerants that are dramatically more efficient than their predecessors, high GWP synthetic refrigerants. It is critical in this field to recognise that:

  1. When you choose the refrigerant in your HVACR system you are choosing its energy efficiency.
  2. Low GWP refrigerants including the natural refrigerants hydrocarbons, carbon dioxide and ammonia offer far greater thermal absorption than high GWP synthetic refrigerants. It is the superior heat transfer characteristic of natural refrigerants that deliver superior HVACR energy efficiency.
  3. High GWP synthetic refrigerants were popularised when we simply didn’t have the engineering that we have today. Modern engineering enables the safe use of energy efficient refrigerants.
  4. The new Low GWP synthetic refrigerants (HFOs, hydrofluoroolefins) are reported to be more energy efficient than their high GWP predecessors. The ARA has yet to see enough data to fully endorse this view.

There are three strategies that are fundamental to vapour compression system management. Future proofing is the first. The advent of low GWP refrigerants and the phase down of high GWP refrigerants is inevitable[4]. To future proof your HVACR system you need to be considering low GWP refrigerant-based technologies before High GWP refrigerants are phased out.

Second, consider retrofit solutions. Many HVACR systems can be retrofit to employ energy efficient refrigerants without replacing the entire system.

The third strategy is maintenance. Far too often, HVACR systems lose efficiency for lack of maintenance. The difference can be as much as 40 per cent.

 All Three Factors Plus One

Better energy measurement, in concert with heat load management and new vapour compression technology will deliver dramatic reductions in HVACR energy consumption. We believe savings as much as 70 per cent can be achieved through integrated energy efficiency engineering, but only if the responsible parties fully investigate the range of opportunities and employ the best combination.

Historically, HVACR contractors have tended to focus on vapour compression without addressing the other two factors. Facilities managers have not fully embraced the energy efficiency available from HVACR and tended to exclude building occupants from the optimisation of HVACR energy efficiency. Clearly, this includes a life cycle cost benefit analysis and the use of financing systems that reflect the energy efficiency benefits available.

The optimal HVACR energy efficiency will be achieved when all three energy efficiency strategies are incorporated and decision-making is raised to the level of the organisation that has the ability to investigate, compare and resolve financial, productivity and environmental objectives.

[1]  Cold Hard Facts 2, Department of the Environment and the Expert Group, 2013. We have added hot water systems to the total reported.
[2]  Cold Hard Facts 2 based on 2012 data, an updated figure is likely to be higher due to increased electricity prices
[3]  Cold Hard Facts 2 adjusted for total direct emissions as distinct from Kyoto accounting, which is not comprehensive.
[4]   The EU has legislated for the phase down of high GWP refrigerants. This same policy has been adopted by most of the industrialised and the developing world. See the Climate and Clean Air Coalition policy on HFC refrigerants phase down.
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  1. Victor

    Thank Tim,
    Its certainly what I have seen in many buildings that I have worked. Its sad that very little attention is given to these systems and on a very large scale.
    The high rise buildings can certainly benefit from the "Chimney Effect" if they use it. The cold air rushes in through the doors of the ground floors.(see this when you enter a high rise building) When such fresh air is available why it cannot be put to good use? I have always wondered as to why we need to use lights during day? And what can be done to bring the outside light inside? Big warehouses using huge power is surely a huge waste.
    A lot of awareness is needed and also to be addressed to the decision makers.