The above graph displays the impact of the heat wave last week on the temperature and humidity inside my living room while the central heating remained on as described earlier last week. This eight day graph from 1230 Saturday, 1st July 2006 to 1230 Sunday, 9th July 2006 shows this impact from excess heat outside which began to come down at the end of the week coincident with the central heating turned off for 24 hours. The latter occurred from late Wednesday, 5th July 2006 to late Thursday, 6th July 2006. The absence of the central heating due to shutting down the boiler appeared with a dramatic decline in temperature from mid-Wednesday to mid-Thursday.

During these eight days, this temperature logger took 385 readings with one every thirty minutes for both temperature in centigrade and humidity in % relative humidity. As the heat wave continued during the first days of the week, the central heating never permitted the temperature to receded during the night. A temperature minimum level was established which grew higher each day from about 34C on Sunday to about 36C on mid-Wednesday. The temperature then declined to about the 32-33C level by mid-Thursday which made a significant difference. When the temperature reaches 35C and stays there and higher, the real problem from the exceessive heat begins which can be noted subjectively.

Here is the objective measure of what has happened against the background of the factors of influence creating the excessive heat inside the flat includng the change from central heat on to off and then back on again. The humidity increase can also be seen as the rains began after mid week, but it is most important to recognise that the central heat when left on in the pipes under the floor create a high temperature that only goes up and does not come down unless there is a large drop in temperature outside.