Considerations for sustainable data center design
To design a green, sustainable data center, consider methods to improve energy conservation and efficiency. Then, look into green -- or greener -- energy source alternatives.
Most businesses want their buildings, even data centers, to be "net zero" by 2050, which means they source all energy from renewable sources with zero addition of CO2 to the atmosphere. Achieving net zero requires a three-pronged data center design approach: energy conservation, energy efficiency and renewable, preferably on-site energy sources.
Now, as more organizations seek to design their data centers -- or redesign and upgrade them -- for environmental sustainability than ever before, consider how to move your facility toward net zero. This could lead to long-term savings, as well as contributing to the improved health of the planet.
A history of sustainability through temperature and humidity
The Uptime Institute's push for hot aisle/cold aisle data center layout in the 1980s began the trend toward greener data centers. Aisle containment complements this approach by improving both the cooling and energy efficiency of this layout.
Thermal Guidelines for Data Processing Environments, published in 2004 by Technical Committee TC 9.9 of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommended increasing air inlet air temperatures to data processing equipment to as high as 27 degrees C or 80.6 degrees F -- far hotter than the previous 12.8 degrees C or 55 degrees F recommendation at which most data centers operated. Higher temperatures yield a reduction in cooling energy.
In 2007, The Green Grid published the Power Usage Effectiveness (PUE) metric, which became the defacto standard of power efficiency monitoring. Because data centers use so much electricity, you must know and track your data center's energy usage in order to increase sustainability. When the Green Grid first introduced PUE, measurements of 2.5 to 3.5 were the norm. Widespread monitoring of PUE has driven numbers down to levels of 1.5 or better. The best cloud and hyperscale facilities now run as low as 1.1 PUE. You don't have to sacrifice either performance or reliability in order to achieve lower PUE numbers.
In 2014, ASHRAE released research showing that legacy relative humidity (RH) levels of 45%-55% were unnecessary for avoiding static discharge, and that RH as low as 8% still caused no static damage to mounted and properly grounded IT hardware. Evaporating water for humidification uses a lot of energy, which means you can find another huge reduction in energy waste by reducing RH levels in your data center.
By designing with best practices in mind and implementing air containment, you can conserve a lot of energy, maximizing the first factor in sustainability. You can also consider implementing direct or indirect liquid cooling.
You can also find much more efficient computer processing hardware, UPS systems and cooling equipment. "Energy Star"-rated servers significantly improve energy efficiency, especially when IT hardware runs close to maximum utilization. You can also shut down unused servers, replace older hardware with high-efficiency equipment and make full use of energy efficiency features to help minimize idle state power consumption. Consolidation and virtualization also improve hardware efficiency.
Consider implementing high-efficiency power and cooling infrastructure in your data center. This includes transformerless, modular UPSes run at high capacity, higher voltage equipment operation, close coupled in-row or overhead cooling, aisle containment, liquid-cooled rear door heat exchangers, full liquid immersion cooling and direct liquid-to-chip cooling.
Depending on what steps you take to achieve energy conservation and efficiency, the remaining challenge is transitioning to clean renewable energy. Even the best data centers use a lot of energy, and attempts at running large data centers on 100% solar have pretty much failed. The number of solar panels required just take too much space. Operators of large facilities have advantages smaller data centers can't match, such as including hydro or wind power in their site selection criteria.
Consider implementing fuel cells for on-site generation, particularly when you can use methane from land fills. This enables you to use nonfossil fuels, eliminates long transmission losses and helps you reclaim the substantial heat produced by these devices. However, cells aren't perfect. They still produce a carbon footprint, but it's a smaller footprint than oil or coal power generation produces.
ASHRAE Standard 90.4 -- the Energy Standard for Data Centers -- now incorporates credits for on-site renewables and heat reclaim.