Cold storage

James Elwing <jamese [at] phm__gov__au> writes

>I am seeking the names of collecting institutions that have
>(successfully) embraced genuine cold storage, say 10 deg C or lower,
>and certainly below 18 deg C, for a range of materials, as well as
>photographic. ...

The National Library of New Zealand has fifteen controlled
atmosphere rooms with nine of them in the Wellington building, that
have been functioning since 1987.  The smallest of these is 30m2 (at
minus 29 deg. C, cold by most standards) and the largest is 500m2
(for manuscripts and archives at 13 deg. C, 35%RH).  Two rooms for
photographic glass and film have climates at 15 deg. C, 35%RH and 2
deg. C, 30%RH respectively.  The rooms were designed, built and
maintained in line with ISO Standards and they work very well.
Standards for storage can confer an impartial authority to the
contestable allocation of an institution's money. While Standards
may be clear, the process of achieving them can be less than simple.

About fifteen institutions in NZ (sometimes very small museums and
archives) have built controlled atmosphere rooms for photographic
collections.  Others have more modest controls of the climate--using
domestic appliances for dehumidification.  I surveyed eleven of
these institutions in 2005 to assess their range of achievement,
compared to the relevant Standards, and tried to identify their
common problems. Some of the following observations were most
prominent and may be useful to you.

    1.  Nomenclature: calling controlled atmosphere rooms 'cool' or
        'cold' stores can lead to people mistakenly regarding them
        as facilities where the temperature is the only important
        parameter and the control of dehumidification and air
        quality may be overlooked.  This can affect design,
        construction, maintenance plans  2  as well as funding.

    2.  Selecting a consulting or construction engineer with
        relevant experience is important.  The calculation of the
        load (including the room's lighting needs, heat sources
        within the room; collection retrieval patterns, etc.) is
        just as critical as the specification of equipment or the
        integration of climate data into a building management
        system.

    3.  The rooms need to be built like a boat (i.e. watertight)
        especially where you are trying to achieve a significant
        control of the RH.  This idea needs to be thoroughly
        understood by the construction contractors.  Vapour barriers
        need to well sealed, especially around penetrations of
        poly-panel surfaces.

    4.  Chemical dehumidification provides greater stability than
        mechanical dehumidification, especially for lower
        temperature and lower RH rooms--where you may be housing
        colour dye images or acetate film .

    5.  Store rooms with air purification do not need the same
        intake of fresh air, meaning significant energy savings.
        Instances of discomfort and headaches for staff dealing with
        acetate film were also reported in spaces with no air
        purification.  In other stores containing acetate film with
        no air purification, corrosion of cooling and
        dehumidification equipment was reported.

    6.  Sufficient redundant capacity is important to maintain the
        climate in the event of equipment failure or programmed
        preventive maintenance.  Some rooms occasionally fail to
        achieve their target conditions because they are
        sufficiently complex to require more preventive maintenance
        than they presently get.  The frequency of programmed
        preventive maintenance will vary with the equipment (three
        monthly was recommended by one engineer).

    8.  Backup electrical supply is important--especially if there
        is a significant difference between the store climate and
        the climate outside the room.

    9.  For colder rooms with wet-pipe sprinklers, heating the pipes
        with a heat trace cable and lagging with thermal insulation
        can prevent the pipes from freezing.

    10  Air locks, if used, should be large enough to comfortably
        fit trolleys as well as staff.

    11. Waste heat should be used elsewhere in the building (e.g.
        for water-heating).

    12  Compliance with Standards is voluntary, unlike fire or
        electrical regulations, but rooms often achieve a high level
        of stability when their compliance with Standards is the
        responsibility of a building manager and this becomes part
        of a personal performance agreement.

More than two decades after the NLNZ's store rooms were constructed,
there is a much greater body of literature and array of tools for
arguing the benefits that were then intuitively understood.  If you
have any specific queries about the Library's CA rooms--especially
those for photographs, you're very welcome to contact me.

Mark Strange
Senior Conservator of Photographs
National Library of New Zealand
PO Box 1467
Wellington 6140,  New Zealand
+64 4 474 3149
Fax: +64 4 474 3035


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                  Conservation DistList Instance 23:25
                Distributed: Wednesday, January 13, 2010
                       Message Id: cdl-23-25-006
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