The difficulties facing the National Health Service (NHS) are rarely out of the headlines these days and the latest poor satisfaction figures make worrying reading and it continues to struggle to get its operating costs under control. James Henley* from Daikin Applied explains how the HVAC industry can help.
Getting the right balance between optimum performance and cost
Building services account for around half the running costs across the sprawling NHS estate but they are also critical for clinical conditions and the safety and thermal comfort of patients and staff. Getting the right balance between optimum performance and costs is an increasingly challenging balancing act for managers.
Thermal comfort is particularly important in a healthcare setting. Patients recovering from health problems must have the best possible conditions to aid their recovery, which makes temperature and humidity control crucial.
Medical teams also need closely controlled conditions so they can operate at their best, as do the sensitive machines they rely on such as lasers and MRI scanners. The task facing air conditioning and ventilation engineers is to balance these requirements with more energy efficient operation as NHS budgets come under intense pressure.
Matching building loads
At Daikin Applied, we have built up considerable experience in healthcare projects worldwide and have found that inverter screw and centrifugal compressors really come into their own in these environments. Inverter compressors automatically adjust to match actual building loads. This helps the chiller or heat pump cope with the fluctuating demands of hospitals and other medical facilities during the course of a busy day, and at different times of the year.
It is also important that the water flow in the HVAC system varies depending on the actual load demand of the building, which is why Variable Water Flow systems are proving increasingly popular in these settings. They modulate the quantity of water flowing through the system and ensure that pumps work as efficiently as possible to reduce energy consumption without reducing central plant performance.
However, facilities managers are increasingly keen to manage complete systems rather than disparate, disconnected units to ensure loads are shared out and equipment does not run unnecessarily. The Daikin Intelligent Chiller Manager (iCM) has become a popular tool as it helps to optimise performance by ensuring systems run at the right level to meet demand.
In the UK, we also don’t take advantage of the benefits of ‘free cooling’ as much as we could despite our temperate climate. The average ambient temperature in the UK is below 15°C for about 75% of the year, allowing for at least partial free cooling for three quarters of the year.
Any process where there is demand for chilled water on a constant basis throughout the year like a hospital can make use of this type of technology which uses the naturally occurring cool air to pre-chill the water before it reaches the refrigeration circuit and so reduces the amount of work the compressors have to do. This has major positive implications for energy consumption and extending the life of equipment.
Water supplied at 10°C would normally result in warm water returning to the chiller at about 15°C. Therefore, as soon as the ambient temperature falls below 15°C, the chiller can switch into ‘free cooling’ mode, allowing chillers to bypass mechanical cooling.
Daikin has recently released a new hydronic free cooling chiller series using low global warming potential R-32 refrigerant and providing cooling capacities from 252 kW to 1012 kW. This extends the options already offered by the Bluevolution range – see more details here.
Noise is another factor in any comfort equation with patients often needing peaceful conditions to aid their recovery. However, healthcare facilities usually require significant amounts of outside air to reduce the risk of infection transmission by ensuring regular air changes. This does mean, however, that ventilation systems are usually operating at high flow rates which can make them noisy.
Also, many hospitals don’t like to use sound-absorbing materials because of concerns about infection control. Hard and reflective materials that tend to amplify sound are usually preferred as they are easier to clean. This means having a low-noise HVAC system with minimal vibration is very important.
Some FMs address this problem by setting time bands for chiller operation, with unit noise minimized at those times of day when low noise is most needed.
However, this must be done without compromising air change rates. A range of experts identified ventilation as a critical part of any healthcare setting. In fact, Professor Cath Noakes OBE – a leading government advisor in this area – said ventilation was “the most overlooked building safety issue”.
Her work as part of the government’s Scientific Advisory Group for Emergencies (SAGE) during the pandemic was widely applauded for helping to improve understanding of how better building ventilation reduces the spread of disease in indoor spaces.
Professor Noakes said the most significant finding made by SAGE’s Environment and Modelling Group, which she co-chaired, was that far too many of UK buildings are simply under-ventilated despite clear guidelines and regulatory requirements.
“The recommended ventilation rate of 10 litres per person per second of clean air is likely to be very effective for protecting health and well-being, but many buildings fail to achieve this level,” said Professor Noakes.
Monitoring and preventative maintenance
The need to closely monitor indoor air quality (IAQ) has also been raised by England’s chief medical officer Professor Chris Whitty who said it should be “standard practice” in most public buildings, especially hospitals and other healthcare facilities.
Daikin’s IEQ Sensor can monitor and track indoor conditions through a set of IAQ parameters, so estates managers can build up a clear picture of the risk of infection transmission in their facilities – as well as the other problems created by low ventilation rates.
However, this is another element of patient and staff welfare that depends on minimising equipment failure and downtime through preventive maintenance. The ability to keep up a constant level of monitoring – both onsite and remotely – is, therefore, a major benefit and is highlighted in the Healthcare Technical Memoranda (HTMs) that set design standards for UK healthcare buildings.
The information provided by monitoring software like the Daikin on Site system allows equipment owners to plan maintenance schedules based on real data – and avoid the extra costs associated with breakdowns and downtime.
Daikin on Site allows engineers to monitor, manage and control HVAC systems in real time, from anywhere in the world directly from the Cloud. This was particularly helpful during ‘lockdown’ periods when physical access to hospitals and other sensitive facilities was restricted.
Such tools mean it is getting easier to keep all the engineering plates spinning so it is possible to still deliver excellence in healthcare provision while simultaneously driving down energy and operational costs – preserving more funds for frontline NHS healthcare.