How Wattwatchers helps to drive Energy Cost Avoidance Program for Data Centres


First, immediately below, is the infographic version of this case study.

Then, if you want to know more, you can read on to dive deeper into the detail of this excellent energy saving partnership between Wattwatchers Digital Energy and Evergreen Power Solutions (EPS).

Wattwatchers devices capture rich energy data from everything mechanical that generates heat or that rejects heat.

At first it almost sounds too good to be true, but Wattwatchers software and energy upgrades partner Evergreen Power Solutions (EPS) is using high-density deployments of our devices in established buildings to help deliver dramatic electricity savings from computer room cooling systems. 

For example, two nearby data centre sites installed in 2019 for the one client have already shown combined repeatable reduced electricity consumption totalling 240kW, which translates to 2,102,400kWh a year, with verifiable ongoing savings of around $24,500 a month off power bills.

This means a circa $800,000-plus upgrade project can deliver a financially-compelling Return on Investment (ROI) of less than three years, effectively paying itself off through energy efficiency, while also adding other value such as enhanced site optimisation. This is achieved by immediately reducing expenditure on buying electricity month to month, with the potential to last for the life of the buildings.

Bruce Ewen, the Sydney-based CEO of EPS, is now spreading the word on his Wattwatchers-enabled solution model around Australia, and in to South-East Asian markets, after scoring early successes at three commercial-scale ‘proof of concept’ installations with data centre operators, two in Australia and one in Singapore.

Wattwatchers devices and data streams now sit at the heart of the EPS model, know as the Energy Cost Avoidance Program, or eCap, supporting a four-step process:

  1. Measurement and Verification (M&V), based on a strategic deployment of Wattwatchers metering as part of site scoping
  2. Air-flow management
  3. HVAC optimisation and recalibration
  4. Report back to customer on outcomes (with hard data from Wattwatchers)

3 sites in this case study

Data centre operators typically are sensitive about the location and operations at their sites for security reasons, so the three sites featured in this case study are anonymised, but otherwise the details provided below are accurate. They are:

SITE 1: Located in an Australian capital city, this EPS proof of concept project covered four floors, including computer rooms. The pre-investigation of the site early in 2019 identified 78 metering points that needed to be covered by Wattwatchers devices, and 77 devices were installed in March. 

The early stage of the eCap intervention focused on Computer Room Air Conditioning (CRAC) units, with longer term attention likely to fall on further savings available from rooftop chiller systems.

Case study Site 1 shows the major reductions achieved in two stages of the EPS intervention, at the start of June 2019, then again in the middle of the same month, delivering power consumption reductions of about 60 percent in total.

SITE 2: Located nearby to Site 1, this is a two-level data centre with 56 metering points identified in scoping, and 55 Wattwatchers devices installed.


SITE 3: Located in Singapore, this intervention involved installing Wattwatchers devices inside four CRAC units in a data centre.

SITE 4 IS COMING: A further site is now being added in another Australian capital city, with 97 metering points, and the same number of Wattwatchers devices, to cover the entire nine floors of an older-style multi-storey building, again housing a data centre. In this case the facility is operating at near maximum capacity for the available electricity supply from two local sub-stations, and development of a new sub-station would carry a price-tag of >$24 million. So using energy efficiency to open up electrical capacity for more IT infrastructure on the established site is an attractive alternative to major capital expenditure.

Power Utilisation Effectiveness

A key metric used by EPS is Power Utilisation Effectiveness (PUE)*, which for EPS is the ratio of units of energy to ‘units of cooling capacity’. ‘It’s physics,’ says Bruce Ewen. ‘The benchmark for split system air conditioning units used in CRAC units is 1 unit of electricity to 2.85 units of cooling capacity; and for chiller systems, it is 1 unit of electricity to 6 units of chilling capacity.’

EPS uses a subset of the PUE calculation – which it calls a ‘mechanical PUE’, because it is confined to equipment that is either generating or rejecting heat – as a guide for cooling system energy efficiency in any building. The EPS target for a good PUE is 1.3, or even slightly better; while anything above 1.6 signals a cost-effective opportunity for intervention; and the worst Bruce Ewen has seen was a 4 at a site in Jakarta.

*Power Usage Effectiveness (PUE) and its reciprocal Data Center infrastructure Efficiency (DCiE) are widely accepted benchmarking standards proposed by the Green Grid to help IT Professionals determine how energy efficient data centers are, and to monitor the impact of their efficiency efforts.









Identifying metering points

In a typical prospective building, according to Ewen, EPS looks to capture monitoring data from ‘everything that generates heat, and everything that rejects heat’.

Cooling systems are the main appliances rejecting heat, and their energy consumption can be directly monitored by a Wattwatchers device. But many of the sources of heat generation can’t be, because they range from the ‘fabric’ of the building itself, to people in the building (‘bums on seats can each count as the same heat as a 60-watt appliance’), to IT and assorted office equipment such as printers and copiers. (Old-style lighting as a heat source often already has been addressed in many buildings, with swap-outs to operationally cooler, smarter lighting such as LEDs.)

Target financial controllers

EPS is increasingly targeting CFOs and other financial controllers as its ‘target customers’, rather than operations people. ‘We show them how they can implement eCap without it costing them a cent, because they can redirect current dollars being expended on the power bills to get immediate returns,’ says Ewen. 

In some cases, clients also may be eligible to earn tradable certificates under efficiency schemes such as Energy Saving Scheme (ESS) in New South Wales, and the Victorian Energy Efficiency Target (VEET), which can further reduce the ROI period for an eCap project. 

‘If available for any given project, then certificates are like the cream on top of an already good deal,’ says Ewen. ‘ They can offset the cost of the hardware for an eCap intervention, including the Wattwatchers devices. We had one site in Sydney where half of the cost was covered by the ESS certificates, and the customer got a 14-month ROI for their project’. 

Why so many metering points?

‘We’re not allowed to work on live boards, so we have to go close to the appliance itself, such as an air-conditioning unit. This gives us rich data about how electricity is being used at a granular level, while avoiding the disruption, cost and often outright barrier of having to do full site shutdowns to install metering devices.

‘The investment in high density metering underpins the cost saving that EPS guarantees to its customers, such as ROI of 36-months or less. It then proves to our customers that the savings are being delivered where we said they would be, which increases trust in our ability to deliver incomes, and it allows us to provide ongoing tracking of performance to both head off any backsliding, and also to identify additional saving opportunities.’

The EPS process

It’s a simple process, according to Ewen. ‘We whack in all the meters. Then we run a baseline analysis. It’s a dynamic situation. Air conditioning responds to ever changing heat loads. We look at voltage, current, Power Factor – do 1 week to 1 month for the baseline- and we use an algorithm to plot a seasonal graph because a lot depends on ambient outdoor temperatures and we EPS is working with another partner to deliver ambient outdoor temperature by postcode.

‘Our main focus is on data centre activity. Because with many of the buildings we go into being at least a few decades old, we are looking to take them from the 1990s to where we are now in the 21st century, increasing the value and capacity of assets in the the 20 to 30- – take from 1990s to 21st century – Net Present Value – get best results

What’s EPS actually doing to achieve savings?

Ewen gets coy when asked about exactly what EPS does. ‘That’s our IP, and we protect it,’ he says. ‘But the monitoring using Wattwatchers provides the evidence that what we do is working. That’s Measurement and Verification in action. And we don’t walk away once the first part of the job is done.

‘Often there is an ongoing services contract. We aim to go back very 6 months and do a retraining. People leave, and we don’t want the people who replace them, who don’t have the history, to devalue the metering and software. And we definitely do want them to renew the license when it comes due (3-year contracts for internet connection, API connection and software license).’

Building client confidence

EPS has a formula for ensuring that customers gain confidence in ePac’s ability to save them money, while being more energy efficient, without negatively impacting on functionality.

Ewen says: ‘We can guarantee that we’ll do better than a 36-month ROI. If can’t hit 3 years ROI we won’t bother, unless the customer specifically wants to do a longer ROI, which is up to them. Our customers need comfort that energy efficiency is being achieved without any negative impact on functionality. Their priorities are functionality first, energy efficiency second.’

Tradable certificate creation

Energy saving incentive schemes such as the Energy Saving Scheme (ESS) in New South Wales, and the Victorian Energy Efficiency Target (VEET) in Victoria may apply to EPS projects, but not always, and the financials don’t depend on certificate creation.

‘Site scoping needs to include what scheme, if any, that they are involved in. There’s no double dipping allowed across these schemes, and any savings have to be additional. If they do apply, certificates are the cream on the top, and can offset the cost of hardware. We had one site where certificates reduced the ROI time to just 14 months.’

In summary: what EPS does works!

Ewen is pragmatic. ‘In our projects, we’ve proved that focusing on cooling systems works. We have savings ranging from 30-75% of air-con load across all of the projects we have done.

‘Air-con might be 40% of total energy, so EPS can influence 15-22%. We can target any buildings with electricity bills of greater than $8000 a month – data centres, hospitals, libraries, government and private buildings.’

Bruce Ewen’s quotable quotes

‘Data centres wouldn’t exist without some heat rejecting taking place.’
‘Energy efficiency should be the first cab off the rank always as we move further into this century.’
‘Energy teams are KPI’d on reducing kWh … metering and software allow them to prove it’



Infrastructure Usage Effectiveness (IUE) – A new white paper published August 1, 2019

‘A new efficiency metric, Infrastructure Usage Efficiency (IUE) has been announced by a Chinese group, TGGC, which spun off from data center industry group The Green Grid.’


The rising challenge of Data Centre energy consumption has been a significant focus of Australian Government policy-makers for over a decade.

  1. Data Centre Energy Efficiency – Product Profile, Wattwatchers partner Pitt & Sherry, the highly-respected energy advisory firm, produced this report in 2009 for the Equipment Energy Efficiency Committee (E3)
  2. Energy Efficiency Policy Options for Australian and New Zealand Data Centres, Equipment Energy Efficiency (E3): ‘Data centres are high energy users with significant scope for improving the energy efficiency of their operation. In 2013 data centres consumed 7.3TWh (26.3 PJ) of electricity in Australia (3.9% of national consumption), and 0.9TWh (3.24 PJ) in New Zealand (2.1% of national consumption). The trend is for increasing demand for the services provided by data centres (mainly data storage) due to growing use of information technology (IT). Large new data centres use the latest energy efficient technology but older, smaller data centres generally do not. Energy efficiency would improve if smaller older data centres were retired. However, decision makers often lack the knowledge to choose an energy efficient data centre service, or they do not prioritise IT energy efficiency due to other pressures. There is a lack of knowledge available for improving current data centres and their operators often lack the time and budget to keep up with new technologies.’
  3. Big data: A big energy challenge? – ‘While computers provide a reduction in net energy consumption at a community level (through decreased transportation, better manufacturing techniques, etc.) increased computer use has led to significant growth in data centres[i] and a trend towards higher density and higher processing power equipment, causing a rise in localised energy consumption and emissions.’
  4. Australian Government Data Centre Strategy 2010-2015 – ‘The cooling system is a major cost driver for data centres, and interacts with many other data centre systems.’
  5. NABERS for Data Centres