Articles, livre blanc
How much does UPS efficiency actually cost?22/09/2020
David Bond, Board member of Centiel SA and Chairman of Centiel Ltd., highlights why buying cheaper will only cost you (and the environment) in the long run.
The operating efficiency of a UPS solution and its total cost of ownership are closely linked, and the most environmentally friendly systems enjoy ongoing operational cost savings. For contractors, getting the ‘best deal’ for any organisation is important. However, if we take a long-term view and add the cost of air conditioning, running costs, maintenance, repairs and spares to the initial purchase price, what is actually the ‘best deal’, both financially for the organisation and in terms of the environment is drawn into question.
Selecting the most efficient UPS is essential to minimise its running costs and its carbon footprint. Operational efficiencies are often stated by manufacturers as being ‘greater than 99%’, however, this level of efficiency is normally related to offline operation or ‘ecomode’.
This figure is therefore deceptive as no serious data centre ever runs on ecomode, as it means they would be operating on raw mains and only transferring (with a short break in power) to full UPS operation when there is a power problem. To compare the efficiency of UPS solutions, it is necessary to look at their true online efficiency, as this measure indicates the UPS’ efficiency when it is actually working.
The type of battery technology used can also add to the Total Costs of Ownership (TCO) of the system and its impact on the environment. VRLA (lead-acid) batteries are classified as ‘special waste’ and five-year design life batteries will typically be replaced every three to four years (if operated at 20°C) because it is better to replace VRLA batteries six months early rather than one day too late. Only one aged battery in a string will cause the critical load to crash.
Compare this to Li-ion battery technology which only needs replacing every 13-15 years in normal ambient temperatures. Li-ion batteries may be more expensive initially but as well as not needing to be replaced, they do not need air conditioning, further reducing their operating costs. VRLA batteries start to prematurely age at temperatures above 20°C and so require air cooling. This is expensive both financially and for the environment as currently more than 60% of the UK’s power comes from burning fossil fuels.
In Northern European locations such as the UK, using Li-ion means UPS cooling could be provided by the natural air temperature, resulting in significant savings on data centre running costs and, equally importantly, reducing its carbon footprint. UPS maintenance costs also add to its TCO and if we take an overall view about the total financial and environmental burden of the system, then this also needs to be taken into consideration.
When it comes to UPS purchase, there are usually two budgets: one for the capital expenditure and one for maintenance. However, the cheapest UPS are invariably built with the cheapest components which have much higher repair and maintenance costs and are therefore actually ‘cost money’ over the system’s working life.
A UPS such as Centiel’s CumulusPower, using Li-ion batteries, will need just one capacitor change and no battery changes in 13-15 years. An inferior solution will need three capacitor changes and three sets of replacement VLRA batteries in the same period. This increases the TCO and the UPS user will need to dispose of many tonnes of scrap VRLA batteries which the current legislation classifies as ‘special waste’. This is why it is essential to calculate the real TCO of systems to compare the financial and environmental differences.
The next point to consider is right sizing. From an efficiency perspective, the big challenge is that the IT power requirement in most organisations will change over time and selecting a UPS that operates at the optimum point on its efficiency curve is essential.
A system which is too small will be overloaded, compromising availability, while a system which is too large will be inefficient, waste energy and be costly to run. It will also cost more than necessary to maintain due to its size. Scalability and flexibility are therefore essential considerations when ensuring the continual ‘right sizing’ of the UPS.
Today’s state of the art UPS technology offers >97% true online efficiency and a flat efficiency curve for loads above 15%, thereby offering the combined benefits of increased flexibility, scalability and lowest running costs.
It is important for organisations to recognise that purchasing the cheapest UPS system does not “save money” and certainly does not adhere to an environmentally friendly approach. The true TCO (as opposed to a cheap purchase price) for the UPS needs to be fully understood and decision makers must select the right UPS to please their boss, the company’s shareholders and the planet.