Globally, the demand for cooling continues to grow exponentially and is destined to overtake the demand for heating by 2060. While alternative and more sustainable energy sources are being developed, it makes perfect sense to make the best use of the energy available to us.

District Cooling has emerged globally as an ideal vehicle for the centralised production of cooling and distribution to buildings over increasingly urbanised areas. In the UAE, it is common to hear such phrases as ‘Demand Reduction’, ‘ Energy Savings’ and ‘Sustainable Development, not to mention the role of the Internet of Things (IoT) and Artificial Intelligence (AI) in data acquisition and storage, to improve the efficient running of HVAC systems.

Colin Bridges

The District Cooling provider has invested in major capital expenses to build and install a huge network provision of chilled water, to which the building owner connects. Subsequently, he is no longer burdened with the local cost of his building’s chilled water production; all that is required of him is to plug into a plate heat exchanger and draw as much thermal energy as he requires.

Sounds simple?

You might be forgiven for thinking this is a most equitable arrangement for the District Cooling provider and the building owner. Not so.

And why not? Do we not have the technologies to balance things out? Yes, we do. We have made much progress, technology-wise, be it the availability of variable speed pumps, variable flow chillers, highly efficient plate heat exchangers, cooling coils or Smart Control Devices. IoT is poised and ready to play its part, and AI is waiting around the corner to make our building systems ‘self-learning’. So, the primary question is, “Why do we encounter building systems that are operating inefficiently, in so much as contracts are put in place to penalise building owners, when the inefficiency in their building system is passed to the District Cooling provider through the plate heat exchanger in the form of Low Delta T?”

Which begs the question, “Could we apply some HI (human intelligence) to the issue?”

From what I understand, District Cooling providers harvest multiple operating data of all connected buildings, in order to match their supply with demand from the client. There is no doubt that it is necessary to harvest data for planning and operating the District Cooling plant most efficiently.

Across the network of connected buildings there will be efficiency variables, with some operating highly efficiently and others less so. Might it be possible, then, to draw on this rich well of knowledge to identify commonalities between well-operated buildings and those that are less so.

Building systems will display energy use trends over time. Affecting factors, most commonly, would be seasonal climate variations, building use, and the way in which the systems are operated and maintained. It should, therefore, be possible, using analysis of this data, to identify best practice where systems are operating at acceptable levels of performance.

There is consensus in our industry of the importance of not just setting a building to work and proving it can cool in the hottest time of the year, but of its ability to respond to varying demand changes, and therefore afford the possibility of reducing energy consumption and, consequently, cost.

For this to happen, it is clear that the building system elements must be able to respond dynamically to the changes in an appropriate way. As control valves close, under reduced demand, pumps must be able to accurately ‘see’ this and respond directly to reduce energy consumption, when less energy is required, and yet maintain the system balance. When the building requires less energy, the supplier will ‘see’ this and be able to respond by providing less energy.

Temperature and pressure measuring device accuracy, for example, is critical to the performance of the system. The question to ask is, ‘How often is the accuracy drift of such devices checked?’ System commissioning prior to handover will, doubtless, require recommissioning or, better still, continuous commissioning over the life of the building.

To use an analogy, expecting a new car to run perfectly as it was on the day it drove away from the garage, without regular servicing is, at best, foolishly optimistic. Why, therefore, should we expect complex building cooling systems to be any different? Fixing things when they break down is not maintenance, it is fire-fighting.

In the context of District Cooling, who sees these changes in performance, and when? Well, directly, the building operator and indirectly, the District Cooling provider, whose business it is to monitor system requirement in order to match it with supply. Who better, then, to provide data to building owners and operators when inefficiencies show themselves evidenced as Low Delta T syndrome?

A penalty issued for Low Delta T is one thing. An Energy Supply Report, together with an Energy Performance Report suggesting actions or checks that might be carried out in which the system could be made to run more efficiently, quite another. And I suspect a bit more welcome, too!

Signing a District Cooling contract signifies a partnership agreement with responsibilities for both sides. It, therefore, makes perfect sense that each party is content with the agreement and sees in it an equitable arrangement that makes economic sense for both parties. The happiest marriages tend
to be those where there is positive input from both parties, with each recognising the needs of the other and responding appropriately. Contracts that operate in an open and communicative manner, I suspect, are the most successful.

We have the knowledge, we have the technologies and, importantly, we have the need. So what measures can be implemented to positively impact upon system performance, in the short term, for the existing systems, and moving forward, future systems yet to connect?We might consider greater transparency of harvested system data from both the District Cooling provider and the building system operator.

1. This might take the form of a regular E from the building system operator to the District Cooling provider. The District Cooling provider could produce an Energy Supply Report (possibly through building energy bills) providing data of chilled water flow, energy and delta T. These would help identify issues around efficiency, which could then inform any subsequent action-plan to address any poor operating
performance and/or mismatching of demand and supply.

2. Mandatory health checks of devices responsible for measuring, monitoring and harvesting measured data values – critical for efficient operation.

3. Continuous commissioning: This could be a series of checks carried out to verify the efficient operation of key elements within the system, namely pump (VFD), DP sensor(s), PHEX health check, AHU filter check set points being achieved, control sequence for pump staging, and control valve response times.

4. Review of energy tariffs to take account of recorded climatic seasonal variations.

5. A building system Log Book, which might be mandatory wherein all data pertinent to the system operations are recorded, in much the same way as a car service record is maintained for the present and any future owner.
Studies show that buildings that have lower running costs, better indoor climate and well-controlled HVAC systems command higher rents, have higher occupancy levels and a high level of customer satisfaction. All good business reasons to seek improvements in the current status quo.

Colin Bridges is Business Development Director, Belimo Automation FZE. He can be contacted at Colin.Bridges@belimo.ae.

CPI Industry accepts no liability for the views or opinions expressed in this column, or for the consequences of any actions taken on the basis of the information provided here.