insulation has made my house hotter, page-25

I think it is commendable that u measured the temp diff before the insulation was installed and noted the 3 degree difference. I do bleive the poster mentioning to clsoe the doors to capture the night coolness is the way forward.

Although u measured the 3 degree temp difference I would put thsi to you:

When you did measure the temp differences it was probably a cooler period of the year and you were still in the mode of keeping some doors and windows closed due to habit from the winter months so in effect without realsing it your hose was holding the night cool air indoors for longer.

As the sumer approached you were chaning you habit and doing what u have always done ie opening up the air circulation through the house. I am willing to bet that if you did not have the insulation and made those same measurements today (during the hot period) and with the air circualtion from outdoors venting through the house, you may have found that your house would be showing similar measurements ie no or little temp difference or indeed cooler outside than inside.

The answer is that the insulation retains the temp in the house longer PROVIDED that you do not let hot air in from outside.