Green Roofing and Externalities

I had heard a story on the radio while driving to work last week on green roofing,

Green roofs will have a waterproof layer, then a layer of something for the roots to grab onto and which can adsorb moisture. Often Sedium species are planted since they are very drought resistant--don't want to water your roof!

There was a situation in Boston where a large retail outlet had considered the use of a green roof, but decided against it on the grounds that the added expense wasn't worth it. There are a few nice things about a green roof: Heating and cooling expenses are less--especially cooling in the Summer, but the largest benefits are not gained by the property owner. The roof stores and uses rainwater, so this decreases the need for storm runoff capacity. The roofs look better and provide some cooling to the local area, so these things are nice for neighbors.

I am normally fairly libertarian and want the government to do as little as possible, but this is a good example of something local communities would be smart to promote. How they do so is critical: If they just mandate it, then new construction will take place in nearby communities without expensive regulations. If they totally subsidise it, they will quickly go broke. What they need are incentives which are just large enough that much (not all) new construction will use this beneficial technology.

I think it is largely uncontroversial that governments at all levels use their authority to promote things that are socially beneficial and discourage those things which are harmful. This is a more gentle form of power than simply having some things forbidden and others required. Take marriage for example: It is a socially beneficial arrangement--it results (most of the time) in children, and provides a stable arrangement for raising them. That there is a whole legal structure around it,- promotes and encourages couples to participate in it. All well and good.

I think that the above should be the framework considered when looking at expanding the definition of marriage to include types other than one man and one woman arrangements. Quite frankly, arguments which rely on some aspect of "fairness" are simply irrelevant. The question should be; will society reap a net benefit from this change?

The purpose of this post is not to opine on the social benefits or lack thereof involved in changes to our marriage laws, only to frame the profitable areas of debate on the issue.