Better cooling is definitely one reason why data center operators are attracted to colder climates like Iceland, but there is a flaw in this argument. Whilst free cooling is very efficient, in most mainland European climates, adiabatic cooling works really well and allows you to achieve almost the same efficiency.
The maximum outside air temperature in the UK still remains lower than the maximum inlet air temperature of modern equipment, and counteracts the issue of distance.
Adiabatic is all you need
In reality, the temperature in the UK and mainland Europe rarely exceeds 35ºC and our climate does not allow for both hot and humid conditions to coincide, thus meaning the wet-bulb temperature should not exceed 23ºC. Worst case, allowing for global warming to be a factor, a wet bulb temperature of 25ºC is the maximum that need be considered.
Adiabatic cooling works efficiently in Europe’s climate by spraying water onto the dry air coolers located on the roof, where you normally get about a 10ºC temperature variation, enabling you to maintain a temperature of 35ºC even on the hottest summer day.
We have built, and now operate, a data center that makes use of this adiabatic theory, recommended under the ASHRAE guidelines, taking advantage of the above climate factors. Additionally, we require no back up DX cooling except for our plant room, and with the knowledge that the wet-bulb temperature will not exceed 25ºC, alongside the fact that modern servers are warranted up to 45ºC, our design allows us 10 degrees leeway. By letting the data center run hot, with the occasional excursion up to 35ºC on a few days per year, we can guarantee significant cost savings.
Our data center was built to the old CESG IL3 standards and they signed off on the resilience and architecture based on our designs & recommendations at the time. We therefore expect our data center to operate at a power usagfe effectiveness (PUE) of roughly 1.2, given that even the best free cooled data center is unlikely to manage better at 1.1 PUE we think it’s worth the extra 10 percent on our power bill. In addition, our location in Dunsfold Park in Surrey, which houses a large scale solar farm, means our data center is partially solar powered, more than making up for the 10 percent difference.
Latency - keep close
For most services, cloud based or otherwise, latency is a big factor. Ideally you want your data center to be close to your customers, preferably in the same continent. This is hence why you do not tend to find US based data centers serving content to UK businesses or customers. Amazon’s Ireland based data centers are an exception.
Some services are more latency sensitive, but having your data center located in urban areas, i.e. within 100 miles of London, means the latency would be approximately 20 milliseconds.
When you start using undersea links or going to remote areas, such as colder countries (like Iceland for example) you definitely have to factor in a big latency difference. Even on a website a human can see a delay of up to 50 milliseconds, therefore creating a delay of at least that for every single query.
There are also questions to be raised about moving away from urban areas. Out here in Surrey, we get about a 1.5 millisecond latency back to central London hubs, sufficient for all services despite being outside the M25 orbital motorway.
Risking power supply
The advantage of being in relatively built-up areas is the mature and resilient power structure you have access to. It is a gross generalization, but has some common sense value, that the further you go from major populated centers, and the further north, the more sparse the population is and thus the worse your connectivity is.
This is slightly mitigated by the fact that backup power is good. However, any data center operator knows you do not want to be using it unless you have to. If you are having to deal with a brown-out every two months, you are elevating the risk factor, whereas in urban areas it’s more likely you’d face a brown out every two years.
Though Icelandic data centers seem appealing, in reality they are unnecessary. There is no need to go so far afield when you can let your data center run hot with the simple solution of sprinkling water on the roof to avoid any risk to power supply or compromise to your latency.
Kate Craig-Wood is managing director of Memset, a UK-based data center provider