First was addition of insulation.  I removed the defective fiberglass insulation (R-11 at best) and had spray urethane professionally installed.  The cost for this insulation was about $1200 – $1 per board-foot.  Massachusetts picked up 75% of this cost in a rebate (up to $2000) and I will get 30% back on my federal income tax.  At ~R-7 per inch, I will have R-21 in the walls; and NO AIR INFILTRATION!

Next was replacement of windows.  Energy star rated is the only way to go.  I decided upon Sheffield windows, who have a good track record.  They feel very solid and have no detectible air infiltration.  These were $450/each installed, but are large windows.  I will get 30% back on federal taxes for these.
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One of the most cutting edge upgrades I  made was LED bulbs in the recessed lights.  The bulbs I picked were PAR 38 warm white LED floods.  I have seven of these altogether installed and they provide much more light at about 55 watts than the previous 600 watt incandescent fixtures.  Many LED lights cannot cut it for general lighting, but I highly recommend these.

Every day the world uses twice the oil it discovers.  Its scarcity will only become worse as China’s economy grows.