Being located in a part of the world where peak temperatures can be extremely high, Saudi Arabia has a high cooling demand. Identifying a cost-effective comfort cooling solution is therefore an important part of city planning in Saudi Arabia.
In 2012, Ramboll was commissioned to conduct a feasibility study of the implementation of district cooling in a new business park in the capital of Saudi Arabia, Riyadh. Once completed, the park will include the head offices for the Saudi Ministry of Commerce and Industry (MCI) and some of its related authorities.
The feasibility study included a comparison of the advantages and disadvantages of district cooling systems against the alternatives of local, de-centralised cooling systems. The most optimal solution was chosen on the basis of four key parameters: Capital costs, operational costs, life cycle costs and space take-up.
It was found that the preferred solution for cooling would be a district cooling system providing the individual buildings with cooling simultaneously.
Specifications for the system
When Ramboll initiated the project, the client was working on three different options for the concept master plan of the business park. All proposals included buildings for offices, retail and hotels, but the total floor area to be cooled varied between the three proposed options. Ramboll’s work focused on option no. 1, as this option expected the floor area to be the largest, namely 242,200 m2.
The peak effect for the chosen conceptual layout for local cooling was approximately 22.5 MW. Choosing a district cooling system made it possible to lower the total cooling capacity for the district cooling system to 9 MW, because of the impact of diversity of the consumers in the network.
By choosing district cooling instead of local cooling, the MCI could display an increased focus on sustainability and environmentally friendly solutions. Moreover, the expenses related to cooling were significantly reduced, as operating and maintenance costs were to be handled by the supply company.
Detailing the concept
Ramboll found that the most favourable system would include large centrifugal compressors and evaporative condensers, so-called cooling towers. Moreover, the district cooling network should include a very large cooling storage facility of approximately 5.000 m3, hereby allowing the compressor capacity to be significantly lower than for local cooling.
A sensitivity analysis showed that even if the impact of diversity is ignored in the overall cooling profile, a district cooling system will still be preferable compared with local cooling. The sensitivity analysis indicated that the district cooling option would be a solid solution regardless of any uncertainty in the assumptions made for the project.