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Sunday, January 20, 2008

Guest Commentary: Examining the Effect of Housing Density on Open Space

by Matt Williams

Friday in his Guest Commentary, Kevin Wolf covered a lot of well thought out points. I would like to focus on one of those points . . . the effect that decisions about housing density will have on how effectively we protect/use the open space around Davis. Rather than force everyone to reread Kevin’s whole commentary, I have excerpted the portions that focus on density here:
The Housing Element Steering Committee asked the public for feedback on what principles and goals [the committee] should use to prioritize where new growth should occur. The top five highest rated principles translate into placing new housing near the downtown and university and/or close to schools and shopping.

I translate this to mean that Davisites prefer we grow at higher densities than lower densities, or for some that we do not grow at all. For example, Lewis Homes’ Cannery Project will eat up one acre of land for every six units it develops even though its densities will average 8 – 22 units per acre. The reason for the lower average for the 98 acres is because of the land that gets taken up by streets, drainage ponds, parks and non-residential buildings. If we increase a site’s density by six units, we will have save an acre of Ag land or habitat from being lost in the future.

The Steering Committee, the City Council, and ultimately, with any new major development outside of existing city limits, the citizens of Davis should prioritize those developments that do the most good in relationship to the negatives they cause. I

If we think out 30 years and have a 1% growth rate, which would be among the very lowest in the region, we will build out just about every one of the 37 sites presented to our committee if we build at the density proposed for Grande (39 homes on 7 acres) or Lewis Homes (6 homes per acre). In every location, we need to build wonderful, engaging, and highly energy efficient homes, townhouses, condos and apartments at higher densities than in the past to reduce the amount of driving that is needed by residents and to protect ag land and habitat in the region. I hope my work on the Housing Committee helps achieve that.
They say, “a picture is worth 1,000 words.” The following graphic prepared by the Planning Department Staff, takes Kevin’s words and converts them into a very compelling picture.

The story this picture tells is both simple and compelling.
  • If Davis grows at a rate of 300 units per year between now and the year 2050, that will add 12,600 New Units.
  • If those 12,600 units are added at an average density of 8 units per acre, then the developed footprint of Davis will expand 2,472 acres.
  • If the average density increases to 14 units per acre, the footprint expansion will reduce over 1,000 acres to 1,410, and
  • If the average density increases to 20 units per acre, the footprint decreases another 500 acres to 894
20 units per acre is a much higher average density than Davis has historically experienced, but when I look at the three maps, I find the top one is the one with the most appeal. Thursday night I will have the chance to share that opinion with the Housing Element Steering Committee at their Community Workshop at Holmes Junior High School. Don’t miss the opportunity to share your opinion as well.

By the way, the three-map graphic can be just as effective in demonstrating the effect of varying annual growth rates at constant density. Mathematically, at a fixed density of 8 units per acre, the bottom map represents an annual growth rate of 1.2% (300 new units per year), the middle map represents an annual growth rate of 0.7% (170 new units per year), and the top map represents an annual growth rate of 0.5% (120 new units per year). As the smoking Nazi soldier, Arte Johnson used to say, “Very interesting . . . “