David Rhodes, Technical Manager at Albion Valves (UK) Ltd, explains why engineers should take a closer look at valves in the search for energy efficiency and net zero wins in new-build and retrofit projects.
As energy efficiency and carbon emissions targets for buildings tighten, engineers need to search every nook and cranny of their designs to find potential improvements and energy savings. Hydronic systems are a great place to start, but they’re often overlooked as a source of efficient and net-zero building performance. The use of balancing valves in systems is important to ensure comfort and energy savings in all environments, avoiding problems of oversized systems and significant temperature differences in various environments.
It’s not surprising that the energy-saving glory often falls to more visible elements of HVAC systems such as chiller or fan coil unit performance. Yet the more modest elements of these systems such as valves are not only a cost-effective investment, they also deliver a significant boost to overall system performance.
When it comes to driving towards net zero buildings, valves are a small, but mighty tool for engineers and installers.
Three important performance characteristics of modern valves are: control, accuracy and repeatability. These are vital because today’s efficient building designs include tightly-targeted design flows in the hydronic system to optimise the efficiencies of terminal units such as fan coils, heater batteries or simply the shower and tap outlets.
Variations from these intended flow rates can lead to inefficiencies such as excessive use of energy to drive the pump system; or where terminal units which don’t perform at their most efficient or alternatively in their wastage of water. Hydronic valves deliver those flows accurately and consistently – so that the system operates as intended.
But valves aren’t simply about hydronic balance. There are several aspects of net zero building design and operation that can be supported by smart valve specification. For example, embodied carbon is rising up the agenda of modern building design, along with increasing interest in the circular economy. Metal valves are an ideal choice for these considerations since they not only have a long lifetime (reducing their carbon footprint), but they are also recyclable.
Of course, engineers and installers are at the forefront of applying renewable systems such as heat pumps and heat networks. Adoption of this low-carbon approach in all types of building is being actively encouraged by legislation, and while the performance of the heat pumps is often discussed, the correct application of valve technology makes all the difference for successful outcomes.
Heat pumps operate at low flow rates, particularly in variable volume LTHW systems. Accuracy of control is needed to maintain system performance and to achieve energy efficiency. Pressure independent control valves (PICVs) are vital for this type of low-carbon system – they have the range ability and authority of control where it’s needed, for example at fan coil units (FCUs) and heat emitters.
We all know that the drive for net zero doesn’t just apply to new buildings. The commercial property market is responding to legislation such as Minimum Energy Efficiency Standards (MEES) and we’re seeing what’s being called ‘the great refurbishment’ sweep across the UK’s office sector.
Albion has worked with clients on many retrofit projects, and we believe that it’s not always necessary to tear out an entire pipework system to find energy efficiency gains. There are some very cost-effective efficiency and net zero wins to be found with the application of modern valve technology.
This lower-cost approach provides quick payback on the client’s investment whilst helping to reduce their energy bills in the long-term. Preserving as much of an existing system as possible with the introduction of modern valves can reduce the embodied carbon of the project overall. This can be an important point as local councils are increasingly looking at this aspect in planning applications for commercial building refurbishments.
With retrofit projects it’s crucial to take a close look at the building’s existing services. Even if the HVAC system is older, the pipework and terminal units may be in good condition, particularly if the system has been well-maintained.
One way to boost energy efficiency and comfort is to improve speed control on the fan, which optimises air flow over the coil. The outcome is not only better energy performance, but also extra years added to the system life – all for minimal cost and reduced down-time for the building.
Many existing office buildings are facing the prospect of new occupancy patterns, as more businesses introduce hybrid working. These changes can wreak havoc on an existing control system, with heating and cooling potentially operating in empty spaces, wasting energy and creating unnecessary costs. A review of areas such as pressure control installation, and in particular pressure reducing valves (PRVs), in these buildings can help to avert these costs.
Another example of a small change making a big difference is the example of a building hot water system, simply changing a 4-port constant volume valve for a PICV can have a significant impact even on an older system. Switching to 2-port PICVs means that the hot water is delivered to a specific location, only where it’s needed and with no wasted energy.
The introduction of PICVs into an existing HVAC system helps to stabilise temperature range in a building, while also allowing the system to react to heating and cooling demands in different occupied spaces – without overshooting set-point temperatures. Greater control and better accuracy of indoor temperatures are better for the environment as well as occupants.
Naturally, when working on a refurbishment project it’s possible to find systems that aren’t in great shape. In older or dirty systems, prevention is better than cure and there’s no replacement for a robust maintenance regime.
However, engineers can check that a system includes strainers, filter pots and non-return valves all of which can prove very useful in keeping things running smoothly. The careful consideration of backflow products in a system can help to reduce contamination in open-loop systems. Optimising cleanliness can support overall system efficiency and reduce future breakdowns.
A further product with consideration for those less-than-ideal retrofits in older buildings is solenoid valves. They’re an invaluable preventative measure that can be easily retrofitted to prevent dripping taps, non-closures and leaks, and provide energy savings particularly in buildings where occupancy diversity varies considerably.
Pressure reducing valves (PRVs) are also a useful choice for new-build and refurbishment projects. They are designed to control the pressure of incoming water from the mains supply. This external pressure can be unpredictable, so the PRV prevents surges of high-pressure water that could damage crucial system elements such as boilers, as well as causing leaks in pipework.
As water is an increasingly precious resource, PRVs can also play an important part in reducing its wastage by reducing the outlet pressure of taps, achieving significant water savings over time.
PRVs, non-return valves and solenoid valves are good examples of how inexpensive updates can make systems easier for building owners to manage their HVAC systems by helping to prevent breakdowns and call-outs. While not directly related to net-zero, any technology that extends the lifetime of systems subsequently reduces the operational carbon footprint of a building by reducing the need to replace equipment.
Building services can make a significant contribution in driving net zero in our built environment. It’s becoming more challenging to find potential savings as targets are set ever-higher.
However, at Albion we believe that with attention to the details of a hydronic system, particularly in valve selection, there are energy and costs savings to be found. Valves can provide a cost-effective solution that not only meets building efficiency and carbon targets, but also supports longer operating life for the system.
Whether it’s a new-build or retrofit project, correct valve selection can help designers achieve the system performance they’re looking for.