VENTILATION
To protect occupants from unintentional air leakage, air barriers must be designed and tested to ensure the construction is fit for purpose.
Issues with mould Air ingress causes major issues with moisture ingress and condensation, leading to mould in some facilities. Mould is a major problem in many parts of Australia, and can be disruptive to clinical operations, and costly to clean and remediate, as seen recently in Western Australia. In tropical coastal regions, warm wind transports moisture into poorly sealed buildings. Condensation occurs when the humid air encounters cooler surfaces in the conditioned air space and inside the walls. Special attention is required when constructing hospitals in these climates to ensure that moisture is removed from the outside make-up air, that ventilation is designed correctly, and that buildings are built airtight. Leaky building envelopes are a major
factor for pollution ingress into a hospital from bushfires, helicopter exhaust, cooling tower aerosols, and city smog. Nitrogen dioxide has an odour, and is an acidic and highly corrosive gas that can affect our health and environment. A common source in hospital environments is from
infiltration of helicopter exhaust emissions when the helipad is in use. In recent years, a major tertiary hospital commissioned the key supply air intakes to temporarily shut down during helicopter idling and take-off/ landing. It was found that shutting down the outside supply air had little effect on adjacent clinical wards to the helipad, due to gaps in the building envelope. During 2019 and 2020, prolonged exposure to smoke from bushfires caused buildings across the country to be evacuated. Upgrading HVAC filters will not prevent smoke ingress via leaks in the building envelope. Hospital air needs to be kept clean, and care needs to be taken not to exacerbate asthma symptoms during bushfire season.
An ever-higher priority for engineers As Australia edges closer to its climate targets of 2030, improving the energy efficiency of hospitals is becoming increasingly important for Australian hospital engineers. Hospitals are among the most energy-intensive buildings, and reducing energy consumption can have a
significant impact on reducing greenhouse gas emissions. Improving airtightness has shown that demand for air-conditioning and heating can be reduced by up to 15%, leading to major savings in electricity bills, and meaningful reductions in energy consumption. To achieve airtight clinical spaces in healthcare buildings, the design should be reviewed to ensure continuity of the air barrier around penetrations, transitions, and interfaces. The construction crew must be aware of the design requirements., and audits should be performed at key stages of the project to ensure compliance. Air leakage should be validated to ensure that design requirements are met which can be implemented in individual clinical rooms, the building façade, and whole building. In addition to commissioning, airtightness testing should be carried out every five years in critical areas. This recommendation is made as air leakage can increase over time due to structural movement, day-to-day wear and tear, refurbishment, repairs that penetrate the air barrier, and material shrinkage and degradation. Through testing, these issues can be identified and addressed, leading to improved indoor air quality and reduction in energy consumption, lower power bills, and a reduced need to purchase carbon offsets. Via appropriate design and validation of the air barriers, the airflows in the facility can be better managed to reduce the risk of cross-infection, and the ingress of external contaminants and achieve higher energy efficiency. This will ultimately both result in better patient and staff health outcomes, and lower the costs of operating the facility.
Further reading n Exclusive: 11,600 people caught Covid in hospital and died. The Telegraph. 8 November 2021. https://tinyurl. com/2xmdexys
n Streifel A, Geeslin A, Nelson, G. (2006). 231. Airborne Infection Isolation Room Leakage Analysis. 231-231. 10.3320/1.2753382. AIHce Conference 2006.
n Veale HJ, Dale K, Ampt F, Kalman T, Kaufman C, Gibson E et al. COVID-19 Hospital-Acquired Infections Among Patients in Victorian Health Services (25 January 2020- 15 November 2020). Final Report. Victorian Department of Health.
n Acknowledgment
This article, titled ‘Building the fabric for infection control and energy efficiency’, was previously published in the July 2023 edition of Healthcare Facilities, the official journal of the Institute of Healthcare Engineering, Australia. HEJ thanks the IHEA, the author, and the magazine’s publisher, Adbourne Publishing, for allowing its reproduction here.
November 2023 Health Estate Journal 31
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