FYI in the 70's and 80's I was an insulation contractor and will be happy to help you with some hints on reducing energy costs and improving your insulation and ventilating needs. You don't have to have a contractor, much is easily done on a do-it-yourself basis.

Lets go one step at a time. The major loss on most properties is the heat being lost out of the attic area. Since heat rises it stands to reason that the greatest pressure would be applied in an upward direction. So, on the 1st day of the fall when your roof is covered by frost or a light fall of snow, take a walk outside and simply look at your roof. If you see spots that are showing snow or frost melting and the rest of the roof isn't, or if your roof is clear and your neighbors isn't, there is a good chance that you have warm air leakage into your attic space.

If you have an indication that this is taking place, get your step ladder out and a flashlight, locate the attic hatch, usually found in a closet that leads into the attic area through a push up door, stick your head in the attic and have a look around.

Things to look for in and around your attic;

1. before you turn on your flashlight have a look around in your attic and see if you can see any place where light is showing through. This is important as air circulation is needed in a well insulated attic to remove any moisture build up. No light, you need ventilation. Rule of thumb for ventilation is; 1 sq. ft. of venting for every 300 sq. ft. of attic in a cross ventilated situation. Ventilated Soffit and a ridge vent usually provide good venting as long as you can see light all the way around. Quite often if insulation has been added the air space between the top of the insulation and the roof sheeting gets cut off. If you find this situation a foam ventilation tunnel may need to be added.
2. feel the air in the attic and see if it is cold or warm up there. If you find that the attic area is nearly as warm as the living space then there is definitely an insulation deficiency.
3. check the exterior edges of the rooms where the walls meet the ceiling. Do you see any black starting to form there? If so you have an infiltration of cold air bypassing your insulation and coming in contact with the drywall or other interior cladding where the warm air is being lost and contacting the colder outside air. This is a condition that is increasingly a problem and will make a problem for you if you are tryuing to sell. This condition creates mould and that is a real red flag for building inspectors doing an inspection for a prospective buyer. The black material you see is mould and bad news.
4. put your hand into the insulation and feel for dampness, if you find any then you have to look at your ventilation and also the amount of the insulation if any.
5. turn on your flashlight on a cold morning and look at the underside of the roof sheeting. If you see frost on the roofing nails that protrude through your sheeting, again you will need to increase the ventilation and insulation. As well look for dampness on the underside of your sheeting, if you find any then vents and insulation need further investigation.
6. looking at the outside of the house again, if you have icicles hanging from your eaves or trough then you have heat loss and insulation will be required.

That's enough for now. I will continue to add some additional hints periodically or if you have a question let me know and I will be pleased to help where I can.

Bruce Kerr