Sustainable Preservation Practices for Managing Storage Environments WELCOME Webinar: South Central Region December 15, 2010
Introduction Presenters James Reilly Image Permanence Institute, RIT Peter Herzog Herzog / Wheeler & Associates
Sustainable Preservation Practices for Managing Storage Environments About this project An Education and Training Grant from the National Endowment for the Humanities, Division of Preservation and Access
Webinar Format One-way conversation No two-way audio Use chat pod to ask questions Moderators will relay questions to presenters Wired connection preferred Full Screen Option desirable for best viewing
Today s Theme: Working with Regional Climate
Concepts We ll be Using Dew Point (Absolute Humidity) Temperature that represents the amount of moisture in air Relative Humidity ( %RH) Temperature Outdoor air becomes indoor air
Goal: Understand Indoor / Outdoor Moisture Relationships Indoor preservation conditions depend on ability to deal with outdoor moisture Summer Winter Key idea: Ability of systems to modify outdoor moisture determines possibilities for good preservation conditions indoors
Tools We ll be Using: Free Web Tools www.dpcalc.org www.pemdata.org
Step 1: Choose an Annual RH Range Example 30 % to 60% RH for your Collection Avoids most damaging extremes of RH From expansion, contraction From mold and fast rate of natural aging Moisture control (Dew Point control) is the challenge Temperature choices and preservation quality will depend on attainable Dew Point
Step 2:What Are the Implications of Your RH Range? The Chosen indoor RH Range (30-60%) implies a combination of temperature and dew point Examine summer and winter conditions separately Flatline (same conditions indoors all year round) or gradual transition between seasons?
Dew Points, Temperatures, and PI Values at 60 % RH Space Temp Space RH Dew Point Temp (Moisture Content) PI 85 60% 70 12 80 65 15 75 60 21 70 55 30 65 51 43 60 46 55 55 41 80
How to choose? Determine Dew Point you can achieve Say, Dew Point is 55 ºF If you want RH of 60%, temp can t be lower than 70 ºF Preservation Index is only 30 (rather poor) Or, pick a PI Say, PI of 55 with an RH of no more than 60% You would have to lower your Dew Point to 46ºF, and set a temperature of 60ºF
Things to Note Dew Point (moisture content of indoor air) establishes a set of tradeoffs High T, poor PI Low T, better PI but high %RH Explore w/ DP Calculator at www.dpcalc.org Only at low indoor DP can both cool T and High PI be achieved Flatlining at summer conditions all year means poor preservation quality
Look at Outdoor Conditions Assume you can achieve a DP in summer of 50 ºF How much work needs to be done to remove moisture from outside air? How big is the dehumidifying task for your system? Pull up outdoor data on www.pemdata.org Zero in on DP graph for summer See how much time outdoor DP is too high
What About Winter? Challenge in dry climates is to raise DP to make possible 30 % RH indoors How much work needs to be done to humidify outdoor air to achieve 30 % RH? Assume you can achieve a DP of 33 ºF (T is 65 ºF, PI is 98 Look again at Outdoor data
Dew Points, Temperatures, and PI Values at 30 % RH Space Temp Space RH Dew Point Temp (Moisture Content) PI 85 30% 50 25 80 46 32 75 41 46 70 37 67 65 33 98 60 28 127 55 24 189
Recapping Most South Central climates have a large dehumidification load in summer Most have at least some need to humidify in winter The capability of systems to accomplish DP control to desired levels determines the combination of Temperature and preservation quality attainable
Flatlining or Seasonal Adjustments? Summer and winter conditions are a challenge for many building systems Reasonable approach is to move setpoints for temperature to take advantage of winter conditions where a combination of lower T and High PI is easier and more economical to achieve Lower outdoor DPs Less heating cost
Working Example Participants: Suggest a South Central Location and presenters will work through the indoor / outdoor tradeoffs
Conclusion Thanks to all participants Next Webinar will be January 12, 2011 at 2 PM EST Topics: North Central Region Theme: Determining the Dew Point control capabilities of your system From mechanical drawings of system From measurement of actual space data