Heating, air conditioning, and ventilation of healthcare facilities play an essential role. They are vital to maintaining a safe environment and protecting not just patients but also medical staff, other employees, and visitors. Hospital operators can achieve this goal using properly designed and developed HVAC systems that allow the separation and isolation of infectious patients. The division of air channels reduces the risk of airborne diseases infecting other users of the healthcare facility. As we battle the global coronavirus pandemic, there is much concern about the possibility of airborne transmission of SARS-CoV-2 – also known as COVID-19 – from patients to staff in healthcare facilities.
ASHRAE’s answers to the pandemic
The HVAC industry is well aware of this justifiable concern and the importance of its systems in reducing the risk of COVID-19 infections in hospitals. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) provides guidance on the design, operation, and maintenance of HVAC systems. Soon after the pandemic outbreak, it published a detailed review of how to prevent the spread of the coronavirus in healthcare facilities. Contrary to some of the CDC research findings, ASHRAE advises against disabling hospital HVAC systems, and this is for a reason. Unconditioned rooms can lead to vulnerable patients being subject to potentially harmful, hot temperatures, which can further lower their resistance to infections. Instead, ASHRAE recommends increasing filtration and ventilation as a way to reduce the concentration of the virus particles and decrease the possibility of airborne transmission.
Hospital HVAC essentials
Hospital heating, ventilation, and air-conditioning systems are too important to be disabled or even reduced. They maintain air quality, provide comfortable temperature and humidity conditions, and offer infection-free environments. They also play an essential role in isolating infectious patients, preventing the circulation of airborne pathogens among other patients, medical staff and visitors. Hospital HVAC systems frequently also have to provide stable environments for diagnostic machines, with set limits on variables like moisture content and temperature range. So as you can imagine, many different functions can only mean that designing, developing, maintaining, and updating HVAC systems in hospitals is a demanding job.
The challenge of hospital HVAC design
There are numerous, sometimes conflicting, demands that HVAC engineers need to tackle. The most common ones include meeting safety and comfort requirements from different groups while reducing energy consumption and achieving cost efficiency. For instance, in cardiac-surgery operating theatres, where procedures can be lengthy, surgical teams generally want low temperatures to mitigate time spent robed in medical gowns and masks. Clinicians generally feel, however, that lower temperatures have a detrimental impact on surgery patients. To address this potential conflict, HVAC engineers need to design a system that allows rapid raising of room temperature following surgery. HVAC design can also be vital to mitigating against hospital-associated infection (HAI), out of which airborne infections account for 5 to 15 percent. That’s precisely where HVAC design governs air quality and engineers play a significant part in maintaining safety in hospitals. Satisfying a wide range of requirements can be tricky. That’s why ASHRAE, the American National Standards Institute, and the American Society of Healthcare Engineering have developed internationally-recognised ANSI/ASHRAE/ASHE Standard 170.
Setting the standard in the ventilation of healthcare facilities
The purpose of Standard 170 is to define ventilation-system design requirements that provide environmental control for comfort, odours, and removal of microbes in healthcare facilities. The standard maintains the safety of patients, doctors, nurses, technicians, staff, and the public through the proper operation of HVAC systems. The ANSI/ASHRAE/ASHE standard sets out requirements for hospital spaces such as isolation rooms, protective-environment rooms, ICUs, operating theatres and imaging departments. It also addresses a wide range of outpatient spaces and environments–from surgeries, and sterilisation departments to storage, laundry services, kitchens, cleaning services, and nursing facilities. The 170 Standard also provides detailed information on HVAC utilities such as heating and cooling, AHU designs, exhaust discharges, filtration, air-distribution systems, and energy recovery systems.
Standard 170-2017 is at the heart of healthy HVAC
Understanding the requirements of ASHRAE 170 is essential because it provides a framework for design and sets out the required standards. Any new buildings, additions to existing buildings and HVAC systems, retrofits or refurbishments must comply with it. To make the requirements easier to understand and implement, the 170 Standard comes with detailed design parameters, ventilation rates, exhaust information and required temperature ranges. ASHRAE 170 sets some other important requirements. These include the documents needed for new and adapted buildings, with hospital owners required to conduct an infection control risk assessment before changing the use of an existing system. New HVAC designs for hospitals must allow for easy access to mechanical equipment rooms so that engineers and maintenance staff don’t enter surgical and care spaces. Plant-room floors must be sealed when they are above surgical suites and critical care spaces. The standard also requires providing maintenance staff training so that they can correctly operate the HVAC equipment. The training has to cover an explanation of the design aim, maintenance procedures, temperature and pressure control operation, and acceptable tolerances.
Staying on top of safety and infection control
Staff training is paramount to safety and infection control in hospital HVAC systems. Healthcare facilities that aren’t properly ventilated and maintained can enable the spread of airborne pathogens. The 170 Standard outlines the measures to prevent infections within the hospital environment and ensure the safety of patients, medical staff, and visitors. It also lists the required ventilation rates for the exclusion of bacteria and other microorganisms. Ventilation systems must provide air movement that generally goes from clean to more polluted areas. If any form of variable-air-volume or load-shedding system is used for energy conservation, it cannot affect pressure balancing or the minimum required air changes. One of the best ways to achieve this goal is to implement high-quality filters. They help to eliminate contaminants from entering the facility. HEPA filtration, used for instance in operating theatres, can trap 99.97 percent of particles as small as 0.3 microns in diameter. Another useful way to reduce infection risks is to use ventilation solutions that prevent cross-contamination of intake and exhaust air. That’s where airtight counterflow heat exchangers can play an important part. Their unique design features allow them to significantly reduce air leakage, making them ideal for ventilation of healthcare facilities.
The key to energy recovery in the ventilation of healthcare facilities
Compared to similar-sized working environments, such as office buildings or schools, hospitals are very energy-intensive. Housing high-tech diagnostic machines and medical equipment, healthcare facilities require large quantities of outside air – which in turn further increases the energy required. Energy and heat recovery systems are becoming ever more critical as hospital operators look to maximise potential savings and take advantage of technical advancements that optimise investments. The 170 Standard outlines the most important elements of the energy recovery designs in hospitals. It recommends separating supply airstream components and the exhaust ones, for example by using run-around pumped coils. That’s another area where counterflow heat exchangers can bring outstanding results, recuperating energy at 90% efficiency. This level of recovery wouldn’t be possible without a unique plate design, helping to extend the energy exchange path with a minimum pressure drop.
Counterflow heat exchangers–a winning combination
Standard 170-2017 provides the criteria to control the comfort, unpleasant smells and infectious microbes in hospitals to provide a safe environment. Counterflow heat exchangers are instrumental in ensuring safe and energy-efficient ventilation of healthcare facilities as governed by ASHRAE 170. At Swiss Rotors, we have automated counterflows production to achieve a much higher level of precision than in traditional processes. As a result, they are not only airtight and energy-efficient but also more affordable. Our production requires lower labour overheads and machining space so we can offer top quality products with a lead time as short as two weeks.
If you are looking to design Standard 170-compliant ventilation of healthcare facilities, counterflow heat exchangers may be what you need. Get in touch to learn more.