When I first considered the green building/energy efficiency field, I admit my interest was 40% nerd-out to all the cool and interesting technological applications and 60% well here's an important way to save the planet.
The environmental importance of green building is nothing to understate: building operation accounts for 35% of global energy consumption--the largest portion of that is associated with heating and cooling--while the manufacture, transportation, and construction of buildings and building components alone accounts for 5% to 8% of US greenhouse gas emissions.
Yet there are so many houses, and no matter how many net-zero homes we start building, the majority of the people are living in a building whose carbon emissions could be reduced with available technology but not with the available economics. You can add in land-use concerns about building new buildings on undeveloped land in a world where we already need to be preserving natural spaces as potential carbon sequestration, and it's clear that no matter how nerdily-cool are many products, ideas, and systems available for the buildings of the future, the buildings that are already built are what need attention, even though the money to take an existing structure with yesterday's technology and vastly re-doing it with tomorrow's is not there for the majority of the people who own the majority of present buildings.
What I've found is that I care about "green building", energy efficiency, thoughtful design, how to do retrofits--all of it--for an additional reason, the more I do it--since money is so important in decisions made both by the individuals who own these homes and the companies who are trying to find a niche to make this stuff happen. That reason is value itself, and being part of an industry that takes the time to give people something that really is equal to the advertised value. Green building is about green but it's also about quality, and that is partially because "green" things like saving energy and avoiding wasteful use of materials are really about doing things right rather than just doing them nominally. It's not just shoving in extra insulation, it's installing the insulation in a way that makes it actually perform to the level advertised on the package--since you know, you are paying for that level of performance when you bought the material. It's not just putting on the "eco" windows and gutter option cause somebody told you it's green, it's thinking about how the environment will affect the house so that five or ten years from now the house doesn't fall down due to all the studs around your window being completely rotted out from a hidden leak-- since going into debt for thirty years on a product that only lasts ten is nobody's idea of a good deal. Maybe the house would have cost you more to buy if your builder had taken more time to care about durability details, and yes, new green construction does typically cost some degree more. In the more extreme cases of water-management stupidity and energy-efficiency ignorance, it's almost like buying a car with four wheels verses buying one with three: the one with three is cheaper, but it doesn't function as a car so you still paid too much. You also ultimately pay more for the car you have to drop a thousand bucks on to fix every ten thousand files than the cheap no-frills new car that lasts.
I just don't want people to throw money away on something that is really a stupid deal for them to begin with--or at least, I want other alternatives to having to do that in order to own a building to exist. From an environmental standpoint building a low-quality house is hanus, because all those (carbon intensive to produce and ship) materials went into a stupid product that is likely to contribute to landfill waste sooner rather than later, that land is now occupied in something other than wildlife habitat, food production, or carbon sequestration, and the people who own it might find themselves stuck in money-pit repair problems and held captive to ever increasing energy bills, and who knows, maybe the thing is eventually foreclosed upon and now nobody even gets any shelter from the thing until somebody swoops in and buys it for cheap to demolish it (see landfill waste) and start over again. I don't deny that people need housing and people who can't pay a premium for quality deserve housing of whatever sort they feel no objection to having just because better options exist, but my experience in the industry has driven me to feel the need to advocate for at least understanding what you're getting into, figure out how to add a base level of quality without adding a substantial premium, or just enabling same-cost options that feature quality over other aspects for those who DO value it.