How can I control temperature and relative humidity levels?

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Category: Environments
Posted by Conservation Answers(Questions:33:Answers28)
Answered On 25 February, 2014 12:21 am

Controlling conditions in the building

Consider the local climate outside the building, and how this may affect your museum's ability to control the climate within the building. In the section above we recommended measuring conditions in each of your museum areas to get an idea of the internal climate of your museum throughout the year.

It can be difficult to accomplish and maintain an 'ideal' museum environment. There are a number of practical measures you can take, however, to achieve a reasonably stable environment.

Use the features of the building

Think of your building as a barrier for the collection, buffering it from the external environment. The features of the building and its design can be used to reduce environmental extremes. There are lots of sources of information about good building design for energy efficiency. Much of this information is relevant to museum buildings, even if you occupy an historic building such as a bank, or school. In fact, many older buildings were built incorporating passive environmental design principles, such as thick walls for good insulation and air circulation to avoid dampness.

The actual steps you can take to improve your building's capacity to protect the collections will vary depending on your location and building type. Your building's design and orientation might be its key attributes. In general, a north facing orientation with shelter from prevailing winds will be beneficial. Listed below are some measures you could consider.

  • Maintain your building in good condition. Many problems result from such factors as dampness in walls, leaking pipes and gutters.
  • If heat gain through windows is an issue, consider installing interior blinds on windows to limit the amount of heat coming into the building, or even better, installing exterior shutters, awnings or even a shade cloth. It may be appropriate to plant trees to provide shade, but be careful not to plant them so close as to give insects easy access to the building.
  • Mould thrives in warm, damp, dark, still spaces. Good ventilation and air movement aid in avoiding mould outbreaks. Oscillating fans with doors open are an easy and effective way to improve air movement.
  • Some parts of the building will provide more stable conditions than others. For example, internal rooms are buffered by surrounding rooms, and tend to be more stable than those with an external wall. If you have the luxury of choice, consider displaying the most sensitive objects in an internal room or at least against an internal wall in preference to an external one.
  • Basements or cellars may be cool, but they are also likely to be damp.
  • Attics or roof spaces are often not insulated and tend to be hot and dry. Try not to use these spaces to store materials that are sensitive to these of conditions.


Use of localised microclimates

The above section discussed using the features of a building to modify the internal conditions. In this section we will describe simple measures that can be taken to create local microclimates to house and protect sensitive items.

  • Use of display cases are common steps we take to create a microclimate. In addition to providing security to the items within, display cases can have a buffering effect on the environment. Unfortunately they can also have a negative effect if heat build up occurs from poorly designed or inadequately vented lighting systems.
  • Objects stored in cupboards and drawers will be buffered from the external environment. Care should be taken with the storage of metals and other sensitive items in wooden cabinets, as some timbers exude acidic vapours that can cause corrosion.
  • Storage boxes and the use of acid-free tissue padding provide additional buffering.
  • Artworks housed in frames with glass and with sealed backing boards will benefit from increased environmental and physical protection.
Dislpay case

Dislpay case

Drawers used to store paper items

Drawers used to store paper items


Framing a painting with glass and backing board provides a stable microclimate Framing a painting with glass and backing board provides a stable microclimate

Posted by Conservation Answers(Questions:33:Answers28)
Answered On 16 February, 2014 5:08 am

The most obvious, but not necessarily the best method of controlling temperature and relative humidity levels is to use an air-conditioner.

If you have air-conditioning or you are considering installing air-conditioning you should be aware of the following important points:

- If air-conditioning is used to control the environment, it should operate continuously so that there are not day/night fluctuations.
- Air-conditioning systems have a limited life.
- Air-conditioning systems should be well maintained or you could experience fluctuations in the environment.

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