Photo: UBCO

A new study at the University of British Columbia Okanagan shines a light on how sunlight can be used to disinfect surfaces in your home or workplace.

The COVID-19 pandemic has magnified concerns over how buildings might influence the health of the people who live and work in them. There has been some attention paid to ventilation, cleaning and filtration, however, the importance of daylight has been ignored, until now.

The UBCO research shows daylight passing through smart windows results in almost complete disinfection of surfaces within 24 hours while still blocking harmful ultraviolet light.

Dr. Sepideh Pakpour, an assistant professor at UBCO's School of Engineering tested four strains of hazardous bacteria—methicillin-resistance Staphylococcus aureus, Klebsiella pneumoniae, E. coli and Pseudomonas aeruginosa—using a mini-living lab set-up. The lab used smart windows, which tint based on outdoor light conditions, and traditional windows with blinds. Dr. Pakpour found that, compared to windows with blinds, the smart windows significantly reduce bacterial growth rate. In fact the smart windows blocked more than 99.9 per cent of UV light, but still let in short-wavelength, high-energy daylight which acts as a disinfectant. This shorter wavelength light effectively eliminated contamination on glass, plastic and fabric surfaces.

Traditional window blinds block daylight, therefore, preventing surfaces from being disinfected. Dr. Pakpour noted previous research shows 92 per cent of hospital curtains can get contaminated within a week of being cleaned.

“We know that daylight kills bacteria and fungi,” she says. “But the question is, are there ways to harness that benefit in buildings, while still protecting us from glare and UV radiation? Our findings demonstrate the benefits of smart windows for disinfection, and have implications for infectious disease transmission in laboratories, health-care facilities and the buildings in which we live and work.”

A study from the Harvard Business Review points to natural light and views being among the most sought after by potential employees. Combine that with a push for “healthy buildings” as part of the COVID-19 return to work and employers could benefit from installing smart windows.

“Our buildings need to go beyond sustainable and smart to become healthy and safe environments first and foremost,” says Dr. Rao Mulpuri, Chairman and CEO at View, the company partnering with UBC for this research. “Companies are grappling with how to bring their people back to the office in a safe way. This research provides yet another reason why increased access to natural light needs to be part of the equation.”

Studies have shown that pathogenic bacteria and fungi can survive on inanimate surfaces for prolonged periods, which can lead to disease transmission.

“With the rise of antimicrobial resistance, antibiotics are no longer a silver bullet in treating health-care-associated infections, which cause tens of thousands of deaths in the US each year,” says Dr. Tex Kissoon, Vice Chair of the Global Sepsis Alliance, UBC Children’s Hospital Endowed Chair in Acute and Critical Care for Global Child Health. “The potential for daylight to sterilize surfaces and avoid these infections altogether is promising and should be factored into health-care facility design.”

Dr. Pakpour presented her findings Wednesday at the international Healthy Buildings Conference in Amsterdam.

“Our findings demonstrate the benefits of smart windows for disinfection, and have implications for infectious disease transmission in laboratories, health care facilities and the buildings in which we live and work.”