Human development of almost every kind has a direct, negative impact on climate change. It might be good to clarify that just because you're focusing on HOAs, that is only one of many developments that should be evaluated. Your hypothesis is focused on HOAs, but you are describing how you would survey home owners, which seems like it would kind of change the focus.
If you were to somehow gather HOA development and landscape requirements as set forth by the city or county, it might be better to analyze the effect of those requirements on climate change. Or maybe how many or how much of the HOA developments actually align with those requirements as built. You can still use geographic methods (GIS) to analyze current land use and land cover of HOAs to quantify adherence to city/county ordinance. This would also prevent you from having to go door to door, which is time consuming (and possibly dangerous).
Depending on the "climate awareness" level of the local ordinances, you could do some analysis to demonstrate what it would take (and what it would look like) for the HOA development ordinance to actually have a positive (or maybe less negative) impact on climate and the environment. In other words, find a way to make your research actionable! You could present your findings to your local government in an effort to initiate change.
Personally, I have a strong appreciation for anything that increases awareness and education for planting native. I love the idea that you are attempting to demonstrate the shortcomings of "traditional" HOA development and propose a new standard way of thinking, like planting native grasses (and trees, shrubs, and groundcover). Golf courses are also notorious for their negative environmental impact, so there's another possible target for your research.
