Archive storage heating and humidity control is about keeping a stable, moderate environment, not simply keeping a room warm. A store heated to a comfortable office temperature can dry paper until it turns brittle, while a poorly heated one can sit damp enough to grow mould. Either way, the records pay for it.
For facility managers in older North East buildings, the boiler and its controls are part of the answer, but only part. This article explains what stable conditions mean, how heating changes the moisture balance of a room, which tools do which job, and what to expect from your maintenance arrangements. All gas, boiler and flue work must be done by a Gas Safe registered engineer, and you can check anyone's registration on the Gas Safe Register.
Four terms explain most archive problems.
The key relationship is that warmer air can hold more moisture. If you heat a room without adding moisture, the RH falls. If you let it cool, the RH rises, and at the dew point water appears on the coldest surfaces.
That is why treating temperature as the only target goes wrong. A room heated for staff comfort through a North East winter can drop to very low RH, drying and embrittling paper and adhesives. A room left cold and unventilated heads the other way, with damp air, condensation and a risk of mould.
Fluctuation does much of the harm. Paper, parchment, leather bindings and photographic materials absorb and release moisture as conditions change, swelling and shrinking each time. Repeated swings, whether daily from a heating timer or seasonal from winter to summer, stress fibres, emulsions and bindings in ways a steady, slightly imperfect environment does not. A store that holds a moderate condition consistently is generally safer than one that touches the ideal figure only now and then.
Published standards exist for this, and you should work from them rather than from rules of thumb. The main references in the UK are BS EN 16893, which covers the location, construction and modification of buildings for archive and library collections, and the BSI guidance on storage and conservation of archive materials, PD 5454, which sits alongside the older BS 4971. Editions are revised, so check the current versions and their exact figures through BSI before you set targets or quote them in a policy.
In general terms, many collections are held within a cool, moderate temperature band with RH broadly in the 40 to 60% range. The right target depends on what you hold. Paper and parchment, photographic film, and magnetic media such as tapes and discs each have different tolerances, and some materials are commonly kept cooler or drier than general paper records. Confirm the figures for each material type against the current standard and note which source and edition you used.
A full heritage or collections archive may justify specialist design, tight environmental specification and conservation oversight. An ordinary commercial records store, such as those kept by solicitors, councils, healthcare providers or engineering firms, usually needs good practical control instead: a dry, cool, stable room, no leaks, sensible shelving and records that can be found and kept for as long as they must be. Museum-grade conditions would be an unnecessary cost for most of these.
How long you must keep records, and in what condition, depends on your sector and the type of record. Tax, employment, health, planning and legal records all carry different requirements. Confirm what applies to your own records with your regulator, professional body or legal adviser before deciding how much protection each collection justifies.
Consider a simple illustration. Suppose winter air outside is cool and fairly humid, say 80% RH. Bring that air indoors and heat it by several degrees without adding any moisture, and its RH drops substantially, because the same amount of water is now spread across air that could hold much more. Heat it further and it drops again. This is why stores in older North East buildings with strong winter heating often end up too dry, while unheated basements and ground-floor rooms nearby stay damp.
Where the heat comes from matters. Radiators and fan convectors close to shelving create local hot spots and dry the nearest boxes and volumes faster than the rest of the room. Leaking valves or joints on pipework passing through the store add moisture and the risk of direct water damage. Both are worth checking as part of routine inspection.
A bigger boiler does not make a better archive environment. What counts is how smoothly the system holds temperature. Weather compensation, zone control and sensible thermostat or setback settings keep swings small. Simple on/off cycling, where the system blasts heat and then shuts down, produces exactly the daily fluctuation that damages materials. Where a records room shares a heating zone with offices, its temperature may follow the office occupancy pattern rather than the needs of the collection.
Failing sensors, sticking valves, tired pumps and drifting controls tend to make room conditions erratic before anything breaks completely. Logged temperature and RH data can therefore act as an early warning, prompting an inspection before the next cold spell.
If you seal a room, add ventilation changes or install dehumidification equipment, do not compromise the ventilation that gas appliances need for safe combustion. Any work affecting gas, flues or combustion air belongs with a Gas Safe registered engineer.
Each tool does one job, and problems arise when one is expected to do them all.
One dehumidifier rarely fixes everything. If damp is entering through a leaking roof, rising ground moisture or a failed gutter, the machine will run constantly and the cause will remain. Deal with the source first, then use equipment to hold conditions steady.
LPG cabinet heaters and similar portable fuel-burning units should not be used in storage areas. They release water vapour and combustion products into the room, raising humidity and creating a carbon monoxide risk, and they are a fire hazard around paper. Warmth for a store should come from a properly installed, serviced and controlled system.
Where a plant room feeds an archive, any new equipment that touches gas supply, flues or combustion air must be specified and installed by a Gas Safe registered engineer.
A thermometer reading taken on one afternoon tells you almost nothing. Stability can only be shown over time, using data loggers or building management system sensors that record temperature and RH continuously.
Placement affects the quality of the data.
Review the logs at least seasonally. Expect winter dryness once heating is running, and damper spells in late summer and autumn. Look at daily swings as well as averages: a monthly average of 50% RH can hide a pattern that moves 20 points every day.
Data should be backed by regular walk-rounds. Look for:
Treat it as both a conservation and a health matter. Do not try to clean affected material yourself, as brushing or wiping can spread spores, damage the record and expose staff. Isolate the affected items if you can do so safely, find and correct the cause of the damp, and seek specialist conservation advice on how to treat the material.
Annual servicing and inspection keeps the controls, valves, pumps and sensors that govern room temperature working predictably. It also supports your legal position. Employers and those in control of premises have general duties under the Health and Safety at Work Act 1974, and the Gas Safety (Installation and Use) Regulations 1998 set out duties on gas appliances, including maintenance and, for landlords, annual safety checks. Which duties apply to you depends on your role and tenancy arrangements, so confirm them for your own premises.
Timing matters. Book servicing before the autumn heating season so faults are found before the cold, damp months arrive. Across Newcastle, Sunderland, Teesside and Northumberland, that means completing checks by early autumn rather than discovering a failed pump in the first hard frost. Our guides on annual boiler servicing and winter breakdown preparation cover the wider routine.
A winter breakdown in an unattended store lets the temperature fall, and as the room cools its RH climbs and condensation can form on cold surfaces. Know in advance who you will call, how quickly they can attend and who has keys and access. Emergency callout arrangements and a short written response plan, including who checks the store afterwards, are worth having before you need them.
If you smell gas or suspect a leak, leave the area immediately and call the National Gas Emergency Service on 0800 111 999. Do not operate switches or try to investigate.
The aim for any records or archive space is a moderate, steady environment that you can prove with data, not a warm room. Heating is one tool among several, and its value depends on well-maintained boilers and controls that avoid the swings that harm paper and other media.
Commercial Boiler Solutions is Gas Safe registered, holds a 5-star customer rating and serves commercial properties across the North East and Northumberland. We can inspect and service the boiler systems feeding your records and archive spaces, and put maintenance and emergency callout arrangements in place before the heating season starts. Learn more about our services