"Final Release" of Denver's new zoning code has now been posted:
www.newcodedenver.com
ADU's have been identified as the most sustainable feature in the new code. Not only do they provide some urban housing that should get many cars off the streets, they are the perfect place to put active solar. Note that passive solar access is impossible to provide except on the south end of every block.
Draft 4 allows for the 2-story ADU's that are needed to get solar systems up and out of the shade. As usual, the buyer of solar needs to be aware of the neighbor's trees so that his new system won't be shaded.
Showing posts with label solar access. Show all posts
Showing posts with label solar access. Show all posts
Friday, January 22, 2010
Friday, December 18, 2009
More Solar Access in Denver
Chris Kennel, a thoughtful resident of Southeast Denver, recently submitted his thoughts to Doug Linkhart on the solar access issue:
"At the Thursday Nov. 19 council meeting I spoke with some advocates of solar access because I plan to install a photoelectric array on my roof and am curious about their ideas. Every solar access advocate I spoke with seemed well-meaning, but I didn't find that any of them had thoroughly considered the implications of their plans. That is why I have chosen to write this letter to you.
The four types of solar access that I heard the solar access advocates describe were:
1) passive solar (sunlight entering windows of their homes)
2) solar hot water panels
3) gardening
4) solar electric (photovoltaic) panels
Each of these solar uses functions differently at different times of the year and therefore has different requirements in terms of access to the sun. This means that a one size fits all approach would either not address each area appropriately or be totally overkill for some areas.
Lets look at each area, starting with the most restrictive one: passive solar. Passive solar, used for heating and lighting is most beneficial when the sun is low in the sky in the winter. In the summer, passive solar is unwanted since it adversely affects indoor comfort and raises the cooling costs of a home. If people want direct sunlight in their first story windows during the winter months, then it
would preclude the design of most of our existing city blocks. In the morning during the winter months, the sun is so low in the sky that an object 2 feet high will cast a shadow 10 feet long at 8 am in the morning. At noon, when the sun is highest, the same shadow would be created by an object that's about 5 feet tall. This means that if someone has a window on their first floor, the roof or gable of neighboring single story house that's 10 feet away to the south would very likely shade its
neighbor to the north. To get unobstructed winter light into a house at noon would require the neighbor's house to be located at least 20 feet away if it's a single story. For morning light, the neighbor would have to be about 40 feet away, and this gets even larger if the southern neighbor's home is a two story.
The second most restrictive solar access issue is rooftop solar hot water panels since these are often used for winter heating. For solar panels, the sun is most effective between 10 am and 2 pm. Two single story houses would be fine close to each other as long as the southern neighbor doesn't have a gable facing the north neighbor. If the southern neighbor has a gable or a second story it would
have to be about 26 feet away from its single story neighbor to avoid shading the rooftop panels during part or all of the 10 am to 2 pm timeframe. If the southern neighbor has a two story gable roof facing the north then it would have to be about 40 feet away.
The third most restrictive solar access issue is gardening. This activity usually happens during the summer months when the sun is higher in the sky, and most sun-loving plants like tomatoes require about 8 hours of sunlight per day to thrive. A single story house would cast a 15 foot shadow and a 2 story house would cast a 25 foot shadow during parts of this timeframe. For gables facing north add another 7 feet to these numbers. People with large lots should be fine, but narrow lots would
receive too much shade for the most sun-loving plants. People with narrow lots could grow plants that tolerate partial shade since from 10 am to 2 pm the shadows from the worst case scenario, a two story house with gable would only cast a 14 foot long shadow.
The most flexible solar access issue is photovoltaic panels. These panels function most effectively in the summer months when the sun is more direct and intense. During the winter months, their output is substantially reduced, so winter solar access shouldn't be over prioritized. Photovoltaics function best from 10 am to 2 pm, and it's unlikely that even a two story neighbor would shade the roof of a single story house to the north during this timeframe in the summer. The more likely
source of shading is from a chimney on the homeowner's own house or a tree. Photovoltaic panels have a weakness in that if any part of a single panel gets shaded, it knocks out the entire panel and in many cases the entire array or branch circuit. Even a leafless deciduous tree in the winter can cast enough of a shadow to knock out a photovoltaic panel. So if photovoltaic panels are given some special status with regard to solar access then it may result in severe tree pruning and even removal, especially to the city's larger and older trees.
Since trees have many benefits, it seems important to exempt them from any rules regarding solar access. Otherwise neighbors will be trying to trim the trees that other neighbors or the city (via parks and greenbelts) own. Even at my house I have some trees that cast shadows over 100 feet long during the winter months, and my trees are only medium sized. I live in a suburban neighborhood so these trees don't affect my neighbors much, but medium sized and larger trees in an urban neighborhood could conceivably cast shadows across four or more lots.
Although solar access sounds nice in theory, creating solar access rules in excess of our current bulk planes is certain to cause a lot of problems. For the group of of Denver residents who place a premium on solar access (and I am one of them), the best and easiest solution is to choose a site that has a park, street, drainage ditch, or other form of undeveloped open space to the south. A second option is to buy a house that's located on the northern most part of its lot.
Not all homes in Denver are equal in many regards, and solar access shouldn't be viewed as a right but rather as a feature. Although I might like my suburban house to be within 5 blocks of a light rail station, a park as good as Washington Park, a bike path, stream, and an excellent coffee house, I can't expect the city to give me all these things. Solar access is similar. Solar access is a function of location, topography, and the direction a home is pointed. As such it has value to some people, but it cannot be equal throughout all of Denver.
For people who do not want to move to a home that has good solar access, there are alternatives. Instead of photovoltaic panels, they can buy renewable power through Xcel energy's wind source program. People who want fresh, local produce can join a CSA (community supported agriculture), participate in a community garden, or visit the farmers' markets instead of planting their own gardens. If someone suffers from SAD (seasonal affective disorder) in the winter they can buy a light therapy box (my wife and I have one and it works great) instead of relying on passive solar light.
Lastly, people who want to reduce their heating costs can better winterize their homes as an alternative to using solar hot water panels or passive solar designs. Better winterization will also make a house more comfortable and energy efficient in the summer. All of these are good options for people who do not have the guaranteed solar access they wish for. It's likely that they've chosen where they live due to other redeeming factors.
Thank you also for your hard work on the rezoning project.
Sincerely,
Chris Kennel"
Lots of good common sense from Chris.
Note: As Douglas Farr and myself have been advocating, the best place for your photovoltaic system is on a two story garage on the alley. Xcel energy is already trimming the trees back there to protect the power lines. The most likely source of shade will then be a pine tree to the south. Try to get an agreement with that neighbor to allow you to prune that tree as required. If he won't grant permission for free, offer some money for a solar easement. You'll eventually earn all that money back and more.
"At the Thursday Nov. 19 council meeting I spoke with some advocates of solar access because I plan to install a photoelectric array on my roof and am curious about their ideas. Every solar access advocate I spoke with seemed well-meaning, but I didn't find that any of them had thoroughly considered the implications of their plans. That is why I have chosen to write this letter to you.
The four types of solar access that I heard the solar access advocates describe were:
1) passive solar (sunlight entering windows of their homes)
2) solar hot water panels
3) gardening
4) solar electric (photovoltaic) panels
Each of these solar uses functions differently at different times of the year and therefore has different requirements in terms of access to the sun. This means that a one size fits all approach would either not address each area appropriately or be totally overkill for some areas.
Lets look at each area, starting with the most restrictive one: passive solar. Passive solar, used for heating and lighting is most beneficial when the sun is low in the sky in the winter. In the summer, passive solar is unwanted since it adversely affects indoor comfort and raises the cooling costs of a home. If people want direct sunlight in their first story windows during the winter months, then it
would preclude the design of most of our existing city blocks. In the morning during the winter months, the sun is so low in the sky that an object 2 feet high will cast a shadow 10 feet long at 8 am in the morning. At noon, when the sun is highest, the same shadow would be created by an object that's about 5 feet tall. This means that if someone has a window on their first floor, the roof or gable of neighboring single story house that's 10 feet away to the south would very likely shade its
neighbor to the north. To get unobstructed winter light into a house at noon would require the neighbor's house to be located at least 20 feet away if it's a single story. For morning light, the neighbor would have to be about 40 feet away, and this gets even larger if the southern neighbor's home is a two story.
The second most restrictive solar access issue is rooftop solar hot water panels since these are often used for winter heating. For solar panels, the sun is most effective between 10 am and 2 pm. Two single story houses would be fine close to each other as long as the southern neighbor doesn't have a gable facing the north neighbor. If the southern neighbor has a gable or a second story it would
have to be about 26 feet away from its single story neighbor to avoid shading the rooftop panels during part or all of the 10 am to 2 pm timeframe. If the southern neighbor has a two story gable roof facing the north then it would have to be about 40 feet away.
The third most restrictive solar access issue is gardening. This activity usually happens during the summer months when the sun is higher in the sky, and most sun-loving plants like tomatoes require about 8 hours of sunlight per day to thrive. A single story house would cast a 15 foot shadow and a 2 story house would cast a 25 foot shadow during parts of this timeframe. For gables facing north add another 7 feet to these numbers. People with large lots should be fine, but narrow lots would
receive too much shade for the most sun-loving plants. People with narrow lots could grow plants that tolerate partial shade since from 10 am to 2 pm the shadows from the worst case scenario, a two story house with gable would only cast a 14 foot long shadow.
The most flexible solar access issue is photovoltaic panels. These panels function most effectively in the summer months when the sun is more direct and intense. During the winter months, their output is substantially reduced, so winter solar access shouldn't be over prioritized. Photovoltaics function best from 10 am to 2 pm, and it's unlikely that even a two story neighbor would shade the roof of a single story house to the north during this timeframe in the summer. The more likely
source of shading is from a chimney on the homeowner's own house or a tree. Photovoltaic panels have a weakness in that if any part of a single panel gets shaded, it knocks out the entire panel and in many cases the entire array or branch circuit. Even a leafless deciduous tree in the winter can cast enough of a shadow to knock out a photovoltaic panel. So if photovoltaic panels are given some special status with regard to solar access then it may result in severe tree pruning and even removal, especially to the city's larger and older trees.
Since trees have many benefits, it seems important to exempt them from any rules regarding solar access. Otherwise neighbors will be trying to trim the trees that other neighbors or the city (via parks and greenbelts) own. Even at my house I have some trees that cast shadows over 100 feet long during the winter months, and my trees are only medium sized. I live in a suburban neighborhood so these trees don't affect my neighbors much, but medium sized and larger trees in an urban neighborhood could conceivably cast shadows across four or more lots.
Although solar access sounds nice in theory, creating solar access rules in excess of our current bulk planes is certain to cause a lot of problems. For the group of of Denver residents who place a premium on solar access (and I am one of them), the best and easiest solution is to choose a site that has a park, street, drainage ditch, or other form of undeveloped open space to the south. A second option is to buy a house that's located on the northern most part of its lot.
Not all homes in Denver are equal in many regards, and solar access shouldn't be viewed as a right but rather as a feature. Although I might like my suburban house to be within 5 blocks of a light rail station, a park as good as Washington Park, a bike path, stream, and an excellent coffee house, I can't expect the city to give me all these things. Solar access is similar. Solar access is a function of location, topography, and the direction a home is pointed. As such it has value to some people, but it cannot be equal throughout all of Denver.
For people who do not want to move to a home that has good solar access, there are alternatives. Instead of photovoltaic panels, they can buy renewable power through Xcel energy's wind source program. People who want fresh, local produce can join a CSA (community supported agriculture), participate in a community garden, or visit the farmers' markets instead of planting their own gardens. If someone suffers from SAD (seasonal affective disorder) in the winter they can buy a light therapy box (my wife and I have one and it works great) instead of relying on passive solar light.
Lastly, people who want to reduce their heating costs can better winterize their homes as an alternative to using solar hot water panels or passive solar designs. Better winterization will also make a house more comfortable and energy efficient in the summer. All of these are good options for people who do not have the guaranteed solar access they wish for. It's likely that they've chosen where they live due to other redeeming factors.
Thank you also for your hard work on the rezoning project.
Sincerely,
Chris Kennel"
Lots of good common sense from Chris.
Note: As Douglas Farr and myself have been advocating, the best place for your photovoltaic system is on a two story garage on the alley. Xcel energy is already trimming the trees back there to protect the power lines. The most likely source of shade will then be a pine tree to the south. Try to get an agreement with that neighbor to allow you to prune that tree as required. If he won't grant permission for free, offer some money for a solar easement. You'll eventually earn all that money back and more.
Saturday, November 21, 2009
Druid Zoning
Denver's new zoning code is on track for approval in February, after about five years of hard work. In the last few days, many folks have rallied in support of "passive solar access". It's a big enough groundswell that it has gotten everyone's (except the Mayor's) attention for the moment.
At first blush, it sounds like a great idea, but only one person has attempted to quantify what it really would require in terms of zoning.
Bernadette Kelly of MOA describes "block sensitive height limits" as a solution. Similar to how the context sensitive front setback is calculated, it would regulate building heights based on the current status of what's on the ground. She cites an English "right to light" law that derives from the Druid civilization. To paraphrase: "if a structure has had access to the sun for at least 20 years, it is illegal to ever block the sun from that structure".
It does solve the problem, would satisfy most solar advocates, but it is a bit impractical to implement, and would greatly diminish your neighbor's current property rights. (Full disclosure: the author is a solar advocate, but hopes to profit from the ability to increase density in transit neighborhoods)
It's doubtful that this proposal will see the light of day in this version of the zoning code, but it's not without merit. Some neighborhoods of one story homes and large side setbacks may want to STAY neighborhoods of one story homes and large side setbacks, and there are no tools in Zoning Code draft 3 to help preserve that context. Two story homes have always been allowed everywhere in Denver, and CPD has thus far refused to change that.
Sunday, July 19, 2009
Denver's New Zoning Map is Dropping the Ball on Sustainability
Soon after being named in the top ten cities for sustainability , Denver may damage it's standing because the proposed new zoning code is largely ignoring the benefits of detached accessory dwelling units (dADU's).
First, a little history:
The zoning code rewrite was called for as far back as 1989. Mayor Hickenlooper hired Peter Park to shepherd it in 2004. Meanwhile, preservationists like Jim Lindberg were concerned how the old code was allowing redevelopers to potentially ruin our historic neighborhoods. Blueprint Denver was begun in about 1998 and released in 2002 as the guide for a new code. The Zoning Code Task Force (ZCTF) was appointed in early 2005, consultants were hired, problems identified, and neighborhood contexts were defined.
Along about early 2008, third parties realized that sustainability issues had been heretofore largely ignored by city staff and their consultants. Michael Henry and Don Tressler of INC (InterNeighborhood Cooperation, an RNO), are the most significant of these third parties. Although Greenprint Denver was initiated in 2006 and widely admired, it was two years before Greenprint representatives were spotted at any ZCTF or Blueprint meetings.
At the request of INC, Park then hired Doug Farr to recommend sustainability strategies for the new code. The author wonders why a Chicago based consultant, however well qualified, could be a better choice than a local firm. For example, does Farr know why evaporative coolers are such a great peak power solution for the Denver area? Probably not. It turns out that swamp coolers ARE a zoning issue. No matter, he wrote the book, and made an effort to interview local experts like Michael Tavel.
Also, in the spring of 2007, Bob Sperling and James Van Hemert and myself organized the Friends of Granny Flats after we realized that the Zoning Code Task Force was almost unaware of the existence and popularity of thousands of historic carriage houses in Denver. We gave a presentation to city staff in April 2007 that was well-received and put dADU's on the radar.
Farr gave his report to the ZCTF in September 2008. At that meeting he was asked, "what are the biggest things we can do in Denver?" His reply, "Two things: Share cars and Solar Access". It looks like the private sector is already targeting the former. By solar access, he went on to explain, on north-south Denver streets it means allowing a taller garage with solar panels on the roof, with laws to prevent future shading of it. After the meeting, he took the concept further and proposed, "for sustainability reasons, the code should require the installation of an accessory dwelling unit whenever these alley structures are built."
(Coincidentally, at the same meeting, the housing affordability consultant, Don Elliot, was asked the same question. His reply, "ADU's, reduction of the minimum buildable lot size, and inclusionary zoning." The ZCTF took the first two choices to heart and they are well-represented in the draft code. The affordability recommendations promised ADU's "in a wide range of districts." The efficacy of Denver's current inclusionary zoning law is unclear.)
After staff parsed Farr's report, they issued the Jan. 14, 2009 sustainability memo , and ADU's are prominent. Mention is made of future study of things like solar fences, kind of a tough putt in urban neighborhoods with mature trees. More on that here and here.
Unfortunately, the proposed zoning map is disallowing ADU zoning over most of the city.
Review the Map . Look for suffixes like -B1, - C1 etc. For example, if your neighborhood has U-SU-C you don't get ADU's, but if you have U-SU-C1, you get 'em. B2 & C2 zoning allows them only on some corners, which is better than nothing, but there isn't any B2 and C2 on the map. Why develop a zoning typology and then shelve it? There are a lot more questions like that once you study the map. Please do, and weigh in .
So, in 2009, after all this work, why is the city offering up ADU zoning in less than 5% of the city?
Edit: As of late August 2009, the areas with ADU zoning shown have increased, but they are still insignificant. There is a small amount of A2, B2 and C2 now shown.
Edit(2) As of November 2009, there is tons of ADU zoning shown. Meanwhile, "Friends of Granny Flats" recommended ADU zoning for ALL single family districts.
First, a little history:
The zoning code rewrite was called for as far back as 1989. Mayor Hickenlooper hired Peter Park to shepherd it in 2004. Meanwhile, preservationists like Jim Lindberg were concerned how the old code was allowing redevelopers to potentially ruin our historic neighborhoods. Blueprint Denver was begun in about 1998 and released in 2002 as the guide for a new code. The Zoning Code Task Force (ZCTF) was appointed in early 2005, consultants were hired, problems identified, and neighborhood contexts were defined.
Along about early 2008, third parties realized that sustainability issues had been heretofore largely ignored by city staff and their consultants. Michael Henry and Don Tressler of INC (InterNeighborhood Cooperation, an RNO), are the most significant of these third parties. Although Greenprint Denver was initiated in 2006 and widely admired, it was two years before Greenprint representatives were spotted at any ZCTF or Blueprint meetings.
At the request of INC, Park then hired Doug Farr to recommend sustainability strategies for the new code. The author wonders why a Chicago based consultant, however well qualified, could be a better choice than a local firm. For example, does Farr know why evaporative coolers are such a great peak power solution for the Denver area? Probably not. It turns out that swamp coolers ARE a zoning issue. No matter, he wrote the book, and made an effort to interview local experts like Michael Tavel.
Also, in the spring of 2007, Bob Sperling and James Van Hemert and myself organized the Friends of Granny Flats after we realized that the Zoning Code Task Force was almost unaware of the existence and popularity of thousands of historic carriage houses in Denver. We gave a presentation to city staff in April 2007 that was well-received and put dADU's on the radar.
Farr gave his report to the ZCTF in September 2008. At that meeting he was asked, "what are the biggest things we can do in Denver?" His reply, "Two things: Share cars and Solar Access". It looks like the private sector is already targeting the former. By solar access, he went on to explain, on north-south Denver streets it means allowing a taller garage with solar panels on the roof, with laws to prevent future shading of it. After the meeting, he took the concept further and proposed, "for sustainability reasons, the code should require the installation of an accessory dwelling unit whenever these alley structures are built."
(Coincidentally, at the same meeting, the housing affordability consultant, Don Elliot, was asked the same question. His reply, "ADU's, reduction of the minimum buildable lot size, and inclusionary zoning." The ZCTF took the first two choices to heart and they are well-represented in the draft code. The affordability recommendations promised ADU's "in a wide range of districts." The efficacy of Denver's current inclusionary zoning law is unclear.)
After staff parsed Farr's report, they issued the Jan. 14, 2009 sustainability memo , and ADU's are prominent. Mention is made of future study of things like solar fences, kind of a tough putt in urban neighborhoods with mature trees. More on that here and here.
Unfortunately, the proposed zoning map is disallowing ADU zoning over most of the city.
Review the Map . Look for suffixes like -B1, - C1 etc. For example, if your neighborhood has U-SU-C you don't get ADU's, but if you have U-SU-C1, you get 'em. B2 & C2 zoning allows them only on some corners, which is better than nothing, but there isn't any B2 and C2 on the map. Why develop a zoning typology and then shelve it? There are a lot more questions like that once you study the map. Please do, and weigh in .
So, in 2009, after all this work, why is the city offering up ADU zoning in less than 5% of the city?
Edit: As of late August 2009, the areas with ADU zoning shown have increased, but they are still insignificant. There is a small amount of A2, B2 and C2 now shown.
Edit(2) As of November 2009, there is tons of ADU zoning shown. Meanwhile, "Friends of Granny Flats" recommended ADU zoning for ALL single family districts.
Tuesday, April 14, 2009
Solar Access for Denver Neighborhoods
The Denver Zoning Code has been rewritten, and is on the verge of release for public comment. The issue of Solar Access has been put on hold for at least a few months. This is understandable, as the release of a large, important document like this is very difficult.
Unfortunately, solar systems are being built in Denver with no protections against shading from neighbors.
For more, please see read this document:
Solar Access for Denver Neighborhoods
Unfortunately, solar systems are being built in Denver with no protections against shading from neighbors.
For more, please see read this document:
Solar Access for Denver Neighborhoods
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