ISO 11799 Explained:
Document Storage Standards for Archives & Libraries

1. What Is ISO 11799:2015?

ISO 11799:2015 "Information and documentation — Document storage requirements for archive and library materials" is the international standard that defines the environmental conditions, building requirements, and operational practices for long-term preservation of paper-based collections. It was developed by ISO Technical Committee 46 (Information and Documentation) and is recognized globally as the benchmark for archive facility design.

The standard covers the entire storage lifecycle: building construction, fire protection, shelving, climate control (temperature and humidity), air quality (both particulate and gaseous pollutants), lighting, pest management, and disaster preparedness. It is not a certification — there is no "ISO 11799 certified" label — but it serves as the reference specification that funding bodies, government agencies, and professional conservators use to evaluate whether a facility meets acceptable preservation standards.

2. What the Standard Covers — and What It Doesn't

ISO 11799:2015 addresses nine major areas:

1. Building construction and location — site selection, flood risk, building envelope integrity
2. Fire protection — detection, suppression, compartmentation
3. Climate control — temperature, relative humidity, stability requirements
4. Air quality — particulate filtration, gaseous pollutant limits
5. Lighting — maximum illuminance, UV content limits, exposure duration management
6. Shelving and storage equipment — materials, spacing, load ratings
7. Pest management — integrated pest management (IPM) protocols
8. Disaster preparedness — emergency response planning, salvage procedures
9. Security and access control

It does NOT cover: exhibition conditions (see separate standards), digitization workflows, cataloging metadata, or the content of preservation policies. It is specifically about the storage environment.

3. Climate Requirements: Temperature, Humidity, and Stability

This is the core of ISO 11799 and the section most relevant to dehumidifier selection. The standard specifies recommended ranges for long-term storage of paper-based collections:

For photographic materials and magnetic media, ISO 11799 references supplementary standards (ISO 18911, ISO 18923, ISO 18934) that specify more stringent cold storage requirements — down to 4°C for color film and -18°C for cellulose acetate negatives.

4. Air Quality: Particulates and Gaseous Pollutants

ISO 11799 addresses air quality in two categories:

Particulate Matter (Dust)

The standard specifies that storage areas should maintain particulate concentrations consistent with ISO 14644-1 Class 8 or better (roughly equivalent to a clean office environment). In practice, this means HEPA filtration — minimum H10 grade, with H12–H13 recommended for collections including photographs, textiles, or fragile paper.

Gaseous Pollutants

This is the part most facilities overlook. ISO 11799 explicitly identifies three categories of gaseous contaminants:

• External pollutants: SO₂ (<10 µg/m³), NO₂ (<10 µg/m³), O₃ (<5 µg/m³)
• Internal pollutants: Acetic acid, formic acid, formaldehyde — generated by wood shelving, adhesives, floor coverings, and the collections themselves
• Removal strategies: Activated carbon adsorption, gas-phase chemisorption media, or desiccant rotor absorption

The standard does not mandate a specific technology, but performance verification requires demonstrating that pollutant concentrations are kept below the specified thresholds. For facilities in urban or industrial areas, this effectively requires active gas-phase filtration.

5. Fire Protection, Shelving, and Building Requirements

Fire Protection

ISO 11799 requires automatic fire detection (smoke detectors in all storage areas, connected to a monitored alarm system) and recommends water-based suppression (sprinklers) over gas-based systems for paper collections — counterintuitively, water damage from sprinklers is more recoverable than the total loss from an unsuppressed fire. For areas with irreplaceable materials, water mist systems offer a compromise with less collateral water damage.

Shelving and Storage Equipment

• Shelving must be made of powder-coated steel or stainless steel — not uncoated wood, which off-gasses organic acids
• Bottom shelves must be minimum 150mm above floor level (flood protection)
• Aisles between shelving units must be minimum 800mm for accessibility and air circulation
• Storage boxes and folders should conform to ISO 9706 (permanent paper) or ISO 11108 (archival paper) standards

Building Envelope

The standard specifies that the building envelope must be designed to minimize uncontrolled air infiltration. In practice:

• Vapor barriers in walls and foundations (especially in humid climates)
• Vestibules or airlocks at all external entrances to collection storage areas
• Door sweeps and gaskets on all doors between conditioned and unconditioned spaces
• Windows in collection storage areas should be eliminated or permanently sealed and insulated

6. How to Demonstrate Compliance

Since there is no formal ISO 11799 certification process, compliance is demonstrated through documentation and monitoring data:

1. Environmental monitoring records: Continuous temperature and RH data from calibrated sensors, with documented review of excursions outside acceptable ranges
2. Air quality testing: Periodic measurement of particulate counts and gaseous pollutant concentrations, with results compared to the standard's thresholds
3. Building documentation: Fire system inspection records, pest management logs, disaster response plan documentation
4. Equipment specifications: Dehumidifier/HVAC specifications demonstrating capacity to maintain required ranges under worst-case seasonal conditions

For facilities seeking funding or accreditation, ISO 11799 compliance documentation is often a prerequisite. The standard provides the framework; your monitoring data proves you're meeting it.

Further reading: Complete Humidity Control Guide · How to Choose a Dehumidifier · The Acid Removal Gap