A cool reception area does not tell you what happens inside a closed unit on a humid night. If you are storing books, photographs, leather or valuable collections for months, choose on the basis of conditions around the items. An air-conditioner logo alone does not provide that information.
Start with the things you are protecting
| Contents | Practical requirement |
|---|---|
| Ordinary replaceable household items | Compare the extra rent with their value; inspect for leaks, condensation and persistent musty odours. |
| Books and paper | Stable conditions, suitable boxes and shelving away from water sources. |
| Wine, instruments, art or rare collections | Use the maker’s or conservator’s storage requirements; ask a specialist if an ordinary unit cannot document them. |
| Damp or already mouldy items | Deal with the condition before storage; do not expect the unit to repair damage. |
For books specifically, the Library of Congress preservation guide recommends stable relative humidity no higher than 55%. That is guidance for books, not a universal specification for every possession. Hong Kong’s Observatory climate summary also notes spells of high humidity in spring, so ask about overnight and seasonal control rather than one reading during a tour.
Four questions that test the promise
- What temperature and relative-humidity range do you aim to maintain, and is that stated in my agreement?
- Where are the sensors, and can you show a recent history from the storage floor rather than reception?
- Who receives an alarm if humidity rises or air conditioning stops overnight, and how are customers informed?
- If the promised range is not maintained, what relocation, refund or claim arrangement applies?
Pack for the environment you are buying
Pack only clean, dry belongings. Keep an inventory and check accessible items after the first few weeks. For books, the US National Archives advises avoiding heat and moisture sources. Keep boxes off the floor using permitted shelving, and leave space where needed to inspect them. Do not install electrical dehumidifiers or other appliances without the operator’s permission.
Finally, check the protection terms separately. An operator’s claim to control humidity does not itself say whether mould damage is covered. If mould is the loss you are worried about, get a written answer on that specific exclusion before paying for cover.