Dewpoint Calculator

A Humidity Monitor (above) is a great device to have in every renovation project to check air quality, CO2 levels usually follow RH%, the levels can be entered in the calculator above to assess the risk of condensation of any cold spots in the house. This one can be purchased from Radionics http://uk.rs-online.com/web/4086109.html#header for less than €20, it has the added benefit of being able to check the efficiency of your HRV unit by checking the temperature of the room and the temperature of the incoming air by putting the outdoor sensor into the incoming air stream. The HRV fan speed can be adjusted up or down to keep the RH% at around 50%.

An Infa Red thermometer can be used to check the temperature of Cold Spots or Cold Bridges in your house, if you enter the temperature of the cold spots and the internal temperature into the Dew Point calculator (top) you can see what RH% you need for condensation to occur. If you keep the RH% of the house 10% below the Dew Point humidity you will never get condensation. I bought this model for €95 in Radionics .
http://radionics.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=5075346#header