Greening your Neighbors

I just stuck this post over at This is more of a musing than a question. When building a new home would it be more environmentally responsible to forego the triple glazed windows and put the saved money into insulation upgrades on neighbor's houses? 10 or 20k would go a long way. Likewise, who is greener? someone who builds a net zero house with 40k of PV. or someone who donates 40k to weatherization programs or even buys 4 solar hot water systems for four neighbors?