Boutique hotel / Airbnb with 8 rooms — sanitising between seasons or after every guest?
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I run a small boutique hotel (8 rooms) near the University area, plus 3 separate Airbnb apartments. Each room has a split unit (9,000 BTU Gree), running almost non-stop in summer with guests changing every 2-3 days. I can't sanitise after every guest, it doesn't make financial sense, but I want something solid for reviews — the 'hotel room smell' is often criticised. What rhythm do you recommend and how do you document it for guests/reviews?
What is really happening
The 'wet socks' or musty smell from a unit comes from volatile organic compounds produced by microbial biofilm on the evaporator, and this smell is treated by WHO and epidemiological studies as a sign of active microbial growth, even when nothing is visible. In a unit used almost non-stop in summer, biofilm rebuilds within 6–10 weeks, which is why one annual sanitising does not keep the room clean for the whole season — hence the recommendation of two visits for intensively used spaces with high guest turnover.
- Start with the manufacturer’s instructions.
- Consider operating hours, environment and observations.
- Plan checks and record completed work.
One fixed interval does not suit every unit and home.
- The 'dirty sock' or musty smell from an air conditioner comes from volatile organic compounds produced by microbial biofilm on the evaporator and blower. [Current Microbiology, 2000]
- Mould odour is treated by WHO and epidemiological studies as an indicator of active microbial growth, even when nothing is visible. [PLOS ONE, 2012]
- When a contaminated air conditioner starts, airborne fungal concentration in the room can jump from 40–920 to 5,500–100,000 CFU/m³. [Indoor Air, 2023]
- European standard EN 15780 defines cleanliness classes (low, medium, high) for ventilation systems and requires periodic inspections, at least annually. [CEN / BSI, 2011]
What we do on site
- Visit 1 (April-May) and visit 2 (July), all rooms, scheduled in the morning between check-outs, so occupied rooms aren't blocked.
- Each unit: sealed double cover, foil on furniture and linens, alkaline detergent, adjustable pressure wash of evaporator, roller, pan and hose, low-fragrance sanitising, filters, outdoor unit in place.
- A dated certificate with the room number, which you can display or mention in reviews.
- We air the room for 20 minutes after the visit, before the next check-in.
- See current rates on the Prices page.
What you can do yourself
- Cleaning staff wash the filters weekly, between guests — 2 minutes per room, cuts the smell a lot.
- 30 minutes on 'Fan' before switching off the unit in rooms left vacant longer.
What NOT to do
- Do not mask the smell with room fresheners — guests notice the difference and mention it in reviews.
- Do not skip filters between guests just because 'sanitising is coming in July anyway' — a dirty filter smells regardless.
Prevention
High-turnover accommodation: 2 visits a year for all rooms, weekly filters by staff, dated certificate for guests.
When to call us
0764 012 943, WhatsApp, Monday–Saturday 08:00–20:00; we schedule between check-outs so no rooms are blocked.
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Sources (8)
- link.springer.com/article/10.1007/s002840010120
- link.springer.com/article/10.1007/s002849900435
- pmc.ncbi.nlm.nih.gov/articles/PMC6968652/
- journals.plos.org/plosone/article?id=10.1371/journal.pone.0047526
- www.ncbi.nlm.nih.gov/books/NBK143940/
- onlinelibrary.wiley.com/doi/10.1155/2023/8984619
- knowledge.bsigroup.com/products/ventilation-for-buildings-ductwork-cleanliness-of-ventilat
- www.facilitatemagazine.com/good-practice-legal/explainer/2013/04/04/bs-en-15780-ventilatio
The information on this page is educational and based on cited sources; it does not replace medical advice. We do not do repairs, installation or refrigerant circuit work.