There are smarter folks on here than me, so i thought I'd try 
I've got some irrigation valves that anger me to no end every year. They are in underground boxes with very poor access and tree roots make "the task" more and more difficult each winter and spring.
"The task"... I have an unusual irrigation setup that can't be blown out for the winter. It is designed to be gravity drained, and that works well except it requires the removal of the valves each winter (and subsequent re-installation in the spring). They are connected with unions, so that's not so bad... IN THEORY. In practice, the movements of the earth and roots make them less and less likely to line up.
So my plan is to build an above ground "house" for the valves. I have a choice:
1) keep it like it is, more or less, but in an above-ground box and still re/re the valves each season. Access will be better and earth/roots shouldn't be an issue BUT it will still be a pain in the **** because I have to re-do the electrical each time.
2) insulate the box and heat it over the winter to just above freezing.
MY QUESTION IS THIS:
is there any reasonable way to estimate what a (for example) 2x2x2 box (with or without insulation) would require in terms of energy, let's say over a 4 month period with an average temperature of -10c and maintained at just above 0c? I want to estimate the annual cost of heating it so I can make an informed decision, but I really have no clue how. By "insulated", I'd mean a single layer of rigid insulation panels and spray foam on the gaps sort of thing. I'm not going to go crazy with 2x6 construction and full batt or anything like that. Just a 2x4 and plywood box.
Thoughts?
I've got some irrigation valves that anger me to no end every year. They are in underground boxes with very poor access and tree roots make "the task" more and more difficult each winter and spring.
"The task"... I have an unusual irrigation setup that can't be blown out for the winter. It is designed to be gravity drained, and that works well except it requires the removal of the valves each winter (and subsequent re-installation in the spring). They are connected with unions, so that's not so bad... IN THEORY. In practice, the movements of the earth and roots make them less and less likely to line up.
So my plan is to build an above ground "house" for the valves. I have a choice:
1) keep it like it is, more or less, but in an above-ground box and still re/re the valves each season. Access will be better and earth/roots shouldn't be an issue BUT it will still be a pain in the **** because I have to re-do the electrical each time.
2) insulate the box and heat it over the winter to just above freezing.
MY QUESTION IS THIS:
is there any reasonable way to estimate what a (for example) 2x2x2 box (with or without insulation) would require in terms of energy, let's say over a 4 month period with an average temperature of -10c and maintained at just above 0c? I want to estimate the annual cost of heating it so I can make an informed decision, but I really have no clue how. By "insulated", I'd mean a single layer of rigid insulation panels and spray foam on the gaps sort of thing. I'm not going to go crazy with 2x6 construction and full batt or anything like that. Just a 2x4 and plywood box.
Thoughts?