Borough Council of King’s Lynn & West Norfolk – Free Cooling, Computer Room

The customer

The public-funded local government council for King’s Lynn and West Norfolk borough.

The brief

To design, supply and install an energy efficient cooling solution to a server room for King’s Lynn Borough Council. The overriding objectives for the design of this project were to utilise infrastructure solutions to offer both a low energy and low carbon system.

The solution

Due to the increased resilience of server room equipment, it is now widely known and practiced that rooms can tolerate greater flexibility in the controlled environment conditions of up to 26°C and between 25% & 85% RH.


This resilience has enabled alternative low energy solutions to be considered for these environments.


The room is of a typical layout comprising of a row of rack mounted servers and network equipment with additional UPS back-up, all configured for both hot and cold aisle air distribution.


The room has traditional split system air conditioning systems re-circulating and cooling the air.


The requirement was for a fully automated N+1 (duty, share and standby) system to complement the existing air conditioning.


Air is drawn in through a particulate filter to a mixing box inside the room. The cool fresh air is then mixed with the air drawn from the hot aisle in a ratio to meet the desired conditions, before it is then supplied through an inline fan and distributed to the face of each rack via diffuser grilles mounted in the ductwork.


The supply air is diffused vertically to provide a curtain of air in front of the racks. The air is then drawn through each rack in the traditional way, before being rejected into the hot aisle.


The system will only ever require a small proportion of the hot dry air from the hot aisle, therefore, a pressure relief valve is fitted on the hot aisle side to equal out the positive pressure of the room by introducing external air.


A bespoke control panel, which monitors both internal and external conditions constantly make adjustments to the air ratios to meet the conditions.


If the external conditions are not available for free cooling, then the system will automatically revert back to re-circulating DX air conditioning. Hour run timers are fitted to the panel to give a visual indication of the energy saved.

Technical Specification

Performance Design

Ambient Design:

+32°c Summer

Room Design Temperature:


Room Humidity:


Energy Analysis Report:

Cooling Duty:

47.5 kW

COP (Co-efficient of Performance):

36 COP Free Cooling

COP Air Conditioning:

2.6 COP DX

(1kW energy input = 36kW energy output)

24hr Operation:

47.5 kW x 24hr                                                  1140 kW Cooling

÷COP (36)                                                          31 kW Input Energy Free Cooling

÷COP (2.6)                                                         438 kW input energy DX Cooling

Free Cooling:

Hours per Year:

8,760 Hours

Annual Free Cooling Operation:

7,360 Hours

Annual DX Cooling Operation:

1,400 Hours

Actual Logged Run Amps:


Actual Logged Power Consumption:

1322 Watts

Actual Logged Power per Day:


Actual Predicted Running Costs per Annum Free Cooling:


Actual Predicted Running Costs per Annum DX:


Actual Predicted Savings per Annum:


Costs based on 8p/kWh

Energy Savings per Annum:


Carbon Reduction:

32 Tonnes CO2

SAVE ENERGY                SAVE MONEY                    FREE COOL

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