Server Room Design in a Marine Container

Occasionally, I get the request to design an unconventional server room requiring construction out of standard marine 20/40 foot containers. Due to financial constraints these need to be cooled using air conditioning units which are normally used within office spaces. When calculating heat loading in such conditions, one has to take several factors into account. namely the sun, humidity, outside temperature, and heat dissipated by the equipment within the container. Below is a quick guide.

Calculating Heat Absorbed due to Sunlight.

I will be using a value of  150 watts/m2, of infrared radiation (heat). For practical purposes, this value needs to be gathered by performing a site visit. The most common dimensions for a 20-foot container are 6.1m long, 2.44m wide, and 2.59m high, for a volume of 39 m3Assuming that 3 sides are being heated by the sun, and that the container is an ideal conductor, we have a surface area of: 

(6.1m x 2.44m) + (6.1m x 2.59m) + (2.44m x 2.59m)  = 37m2

37m2 x 150 watts/m2 = 5.5kW = 18,800Btu/hr = 1.6 Tons of cooling

Calculating Heat Generated by Servers

This one is straightforward, and the heat dissipation can be obtained from the manufacturer specs. For example, an HP DL380G8 releases 1725 BTU/hr on a 460Watt power supply.

Calculating Heat Generated by the UPS

Most modern UPS operate with 90% efficiency meaning that one can assume. I usually calculate heat loading by measuring the input current using a clamp meter and assuming that 10% is given off as heat. (I won't go into apparent power) Example:

10A x 230V = 2300 Watts being consumed by the UPS.
Therefore heat given off = 230Watts = 800Btu/hr

Total Heat 

18,800Btu/hr + 1725 BTU/hr +  800Btu/hr = 21,325Btu/hr

Selecting Cooling Equipment 

For the above setup, the closest comfort cooling unit would be a 24K Btu unit.  

Temperature and Humidity Monitoring

I tend to use RoomAlert. 

Easy Ethernet 'Plug & Play' setup for immediate IT & facilities physical environment monitoring. Includes built-in Digital Temperature sensor, Device ManageR software &
Includes external Digital Temperature Sensor. Includes ports for 2 digital sensors, 1 switch sensor or dry contact & port for Light Tower or Relay. Offers advanced alerting by email, email-to-SMS, SNMP, webpage update and more.