What should be the temperature in the library to be maintained? we are from Baguio City and we are using a dehumidifier..

The site of the National Board of Antiquities gives information for care for old books (in Finnish): the temperature should be 17-18 degrees (Celsius) and humidity 50%.
http://www.nba.fi/en/
The site of the american Northeast Document Conservation Center states, that authorities disagree on this matter, but that the most frequent recommendation a stable temperature no higher than 70°F (21 degrees Celsius) and a stable relative humidity between a minimum of 30% and a maximum of 50%.
http://www.nedcc.org/resources/leaflets/2The_Environment/01BasicGuideli…
The library of Congress has information about preserving books on their pages,
http://www.loc.gov/preserv/care/books.html
See also AIC pages
http://www.conservation-us.org/index.cfm?fuseaction=Page.ViewPage&PageI…
You might try asking for additional information in some the addresses above and maby also in our National library, http://www.nationallibrary.fi/index.html and our National repository library http://www.varastokirjasto.fi/lang_en/