Insulation outside concrete blocks?

To the real estate editor: In your response to Mrs. E. W. Marshall of Mount Dora, Fla. (''Ask a Builder'' column of Oct. 2), you recommend putting insulation on the inside of concrete-block housing. Would it not be better to put it on the outside, thereby including the concrete blocks as part of the interior thermal mass of the house?

This helps to reduce the amount of artificial heating or cooling needed to achieve a given level of comfort.

As an experienced adobe builder, you know this, so I can only surmise that you believe outside insulation is not practical, even with modern rigid sheets.

Maybe other readers have some suggestions. Bruce H. Morgan Annapolis, Md.