Catching up to the 21st century, part 13...strawbale wall thickness woes

Floor area is defined as that area within the exterior walls, including wall thickness. This definition poses a problem for my straw-bale home design which is limited to 1,200 ft² of floor area. Straw-bale walls are thick compared to stickframe construction. Assuming 24 inch thick straw-bale walls, my 1,200 ft² floorplan would have 936 ft² of usable floor area (the area within the interior surface of the exterior walls). In contrast, a 1,200 ft² home with 6" stickframe walls would have 1,131 ft² of usable floor area. I love straw-bale homes, but not enough to sacrifice 195 ft² of usable living area.

In May, 2007, with the help of friends, a local architect/straw-bale building advocate and a local straw-bale builder, I wrote a letter to my county planning department and district supervisor requesting a special interpretation of floor area for straw-bale homes. I argued that only 6" of straw-bale wall thickness should be included in the floor area calculation. The county replied in June, 2007. They said that I raised an interesting topic for future green building standards, however, the current floor area definition was not subject to interpretation. I have therefore abandoned my straw-bale design.

Catching up to the 21st century, part 12...neighbor's home construction

July, 2007

Construction started on my land partner's (K) home. This created several opportunities to share infrastructure costs - one of the advantages of sharing land with another party.

• Septic System - K and I installed a 2000 gallon septic tank with a leach field approved for both his home and my home. The system uses chamber leaching devices which are slightly more environmentally friendly than rock trenches due to their smaller footprint.
  
  
• Water Supply System - In my county, a home requires a 5000 gallon water storage tank hooked up to a hydrant for the fire department to use in case of a fire. Both K and I bought 5000 gallon tanks, but we shared the pressurization pump and fire hydrant. The hydrant had to be located between 50 and 150 feet from both homes. Fortunately, I knew roughly where my home would be built. We found a convenient location for a shared hydrant.
  
  
• Drainage System - On my property, the roof runoff through gutters must be directed to a device called a level spreader which diffuses the runoff and spreads it over an appropriately sized land area. K and I shared in the trenching and installation of the level spreader and water lines leading to the level spreader.
  
  
• Electric - The local utility (PG&E) required a connection to the main transformer supplying power to our parcel and the 3 parcels that neighbor ours. K and I shared this connection fee as well as the cost of trenching the underground conduit to a splice box near our future home's utility room.
  

Each of these systems will be ready for a simple hookup in the future when my home is built. Thanks for reading. As always, your comments are appreciated.

The Lowdown on Low-E

***WARNING: This information is specific to Santa Cruz, California!***

Low-emissivity (Low-E) glass coatings are an awesome window feature. With multiple pane insulated glass windows, there are several potential glass coating combinations. The standard offerings from window manufacturers generally perform well thermally in climates that require heating and cooling, but may not apply in all situations. What about coastal climates like mine that have very low cooling demand? What about a home design like mine with a large expanse of South facing glass for passive solar heating?

For this post, I ran an energy analysis of my home using HEED software. I ran the 4 different glass coating scenarios listed below.

1. All double pane windows with LoE³-366^TM on surface #2 (inside surface of exterior pane) and Argon fill.
   
   
2. All double pane windows with LoE²-270^TM on surface #2 (inside surface of exterior pane) and Argon fill.
   
   
3. All double pane windows with no coatings (Clear).
   
   
4. All double pane windows with LoE-179^TM on surface #3 (inside surface of interior pane) and Argon fill.

All other characteristics in the model remained the same for each analysis scenario. I compared total annual heating energy for each of the 4 scenarios. My home design is all electric, so the energy units are kilowatt-hour (kWh). The graph is shown below.


A few comments about the results:

• Two of the coating offerings from one of my potential window manufacturers (LoE³-366^TM and LoE²-270^TM) perform poorer than using no coatings at all (Clear). The reason is that they are designed to reduce solar heat gain in the summer as well as insulate in the winter. In my moderate coastal climate, these characteristics are detrimental to thermal performance. My design wants maximum solar heat gain in the winter. Passive solar heat gain through the windows during the day more than offsets the heat lost at night. The summers in Santa Cruz are not hot enough to require these coatings.
  
  
• LoE-179^TM is an ideal coating for the windows in my passive solar home design. It allows about 90% of the solar heat gain of clear glass, yet limits heat loss to about 66% of clear glass. I will need to specify this coating as a window option. Any added cost from this option is offset by a reduction in solar panels needed to generate heating energy.
  
  
• The analysis was kept simple for posting. All windows within each scenario were kept the same. Further performance gains can be obtained by tweaking individual windows or window groups. For example, windows on the North wall (in the Northern hemisphere) could use high U-value coatings like LoE³-366^TM.
  
  
• Thermal performance can be further improved by using thermal shades at night.
  

The bottom line is that home designers should be careful when specifying window glass coatings. Various climates require various coatings. Fortunately, glass companies can provide suitably coated glass to the window manufacturers for incorporation into your windows. Simple analysis tools can help determine the best coatings for any application. All that's left is to tell the window manufacturer what you want.

Thanks for reading. As always, your comments are appreciated.

Catching up to the 21st century, part 11...scotch broom

Scotch broom is a perennial leguminous shrub that is considered an invasive species in California. If left unmanaged, it can quickly take over a land area. Every year in spring, we practice the ritual of "pulling broom" to keep it under control. We pull in spring because the soil is loosened up from rain, making easier work.

I have questioned the effectiveness of pulling because the scotch broom always reappears. I have heard that there can be an 80 year supply of seeds in the soil around plants that have been freely reproducing year after year. Pulling one of these plants exposes seeds that were buried in the soil around the roots. These seeds germinate in the disturbed soil resulting in another patch of scotch broom next year.

I decided to try an experiment comparing pulling to cutting. In the middle of February, 2007, we pulled waist-high scotch broom west of a north to south running landmark. We cut broom east of this landmark. The nice thing about cutting is that it is quicker and requires less effort. The before and after photos are shown below. Notice how the orange road safety cone came into view - yes it was there before removal.

Before Removal

After Removal

Flash forward to February of 2008. The verdict? In this case, the pulled broom side had fewer plants of smaller size than the cut broom side. I guess you get out what you put in. Cutting takes less effort in a given year, but requires the same - or possibly more - effort year after year. Pulling requires significantly more effort the first year. However, in my experience, it looks like the effort will taper off with continued maintenance.

Thanks for reading. Let me know if you have a scotch broom or other invasive species story.

Catching up to the 21st century, part 10...soft water

February, 2007

My well water is very hard. I would prefer to use well water only for fire suppression (sprinklers) and irrigation. I would prefer all fixtures in the home to be supplied with low or medium hardness water. I do not want to use a conventional water softener because salt (or potassium) is added to:

1. the water as a result of normal use
2. the environment as a result of filter regeneration

What is an unconventional water softener, you ask? Mother nature will drop about 23,000 gallons of rain on my rooftop during an average year. A rainwater harvesting system has the potential to store about 18,000 gallons of this free, soft water. The stored water can either be kept separate and treated for domestic use. Or, it can be mixed with well water, treated for domestic use and supply fire sprinklers. Mixing the water is a little simpler than having separate storage systems for sprinkler and domestic use. Mixing soft rainwater with very hard well water will result in a hardness somewhere between the two extremes. The primary green features of rainwater harvesting are:

• free water softening - without using salt or potassium
• reduced fixture maintenance from hard water scale when mixing treated rain water with well water for domestic use
• preserving groundwater supply by reducing well usage
  

Catching up to the 21st century, part 9...Pyrolox well water filter

January, 2007

Our well water has a barely acceptable level of Iron (Fe) and a barely unacceptable level of manganese (Mn). Capitola Pump, the well installer on our land, recommended an ozonator from Triple O to treat the well water. Ozonators reduce Fe, Mn, hydrogen sulfide (H2S - rotten egg smell) and kill bacteria too. The Triple O is set up with a recirculation pump to continuously filter water in the storage tank resulting in drinking quality water. I heard from people I trust that these units perform well. However, I was concerned with periodic filter and bulb maintenance and continuous electricity use. In a green home design, I think all purchases should strive to reduce initial material use as well as ongoing maintenance and power usage. I decided to use the ozonator as my baseline and try to find a greener solution for my specific application.

A little research on well water treatment comes up with Pyrolox iron filters. These filters reduce Fe, Mn and H2S by catalyzing a reaction which causes the contaminants to precipitate out of the water as Fe, Mn and H2S oxides. Periodic backwashing with water removes the oxides from the filter and rejuvenates the Pyrolox filter media. How often to backwash depends on the quality and quantity of filtered water. More contamination or water use requires more frequent backwashing. Note that Pyrolox filters do not reduce bacteria levels.

I estimated that a Pyrolox filter alone could reduce our Mn to acceptable levels. Two important things are required for a Pyrolox filter to adequately remove Fe, Mn and H2S without additional filtering systems.

1. Contaminant levels must be low enough for Pyrolox to work alone. If levels get too high (>10ppm Fe, >5ppm Mn or >3ppm H2S), another oxidation system like chlorination or aeration must be used along with the Pyrolox. Our Fe level was 0.29ppm (<0.3 required), and our Mn level was 0.089ppm (<0.05 required).
   
   
2. The well pump must produce a high enough flow rate in gallons per minute (gpm) to effectively backwash the filter. High backwash flow rates allow adequate precipitate removal and long filter media life. Our well pump produces 15gpm which meets requirements.
   

A Pyrolox filter backwash valve timer continuously uses electricity, but only about 1/3 that of the Triple O ozonator. With our low contamination levels, the Pyrolox filter media should last at least 15 years (probably much longer). The final factor that settled my decision was that the Pyrolox filter cost 1/2 that of the Triple O ozonator. In my opinion, the Pyrolox filter was a greener solution than an ozonator for Mn reduction in my specific application.

We purchased our Pyrolox filter from Clean Water Store in Santa Cruz. After installation, water quality testing showed that the Pyrolox filter reduced Fe to <.05ppm (a factor of 6 reduction) and Mn to <.o1ppm (a factor of 9 reduction). I have the money saved from this purchase to apply towards a bacteria filter to get equivalent performance of an ozonator. I'll cover that in a future post. Thanks for reading! Your comments are appreciated.

Catching up to the 21st century, part 8...home design continued

January, 2007: I am thinking of doing the home design myself because of my 3D CAD experience. I tried demos of the following programs:

• Chief Architect
  
• Envisioneer
• Sketchup
• Softplan
• Vectorworks

My preference for a decent program focused on home design is Chief Architect.

I modeled a 2 story loft in more detail and started solving problems such as the spiral staircase location. It wants to be centered on the EW width of the house and split 50/50 on the south edge of the balcony. But the upper bedroom closet extends beyond the centerline of the EW width. The bedroom closet will be modified to allow the staircase 25% pie slice to be cut out of either the E or W quadrant of the balcony.

I have been thinking more about water systems and black/grey water systems. I want a pond and a constructed wetland. A consultation with Rana Creek (an ecological design company) on site in late January confirmed my worries about cost and permits. It looks like these design elements will not be included in our plans. We will go with a standard septic and plumb for grey/black water split. We will use low flow or composting toilets to reduce black water output.

January 27, 2007: Met Michele Landegger of Boa Constructor at the Sullivan home tour. She seemed to be the truly wonderful person we heard from everyone. At the Sullivan house she showed pictures of some of her work and told a few stories of her experiences. We went to a local Mexican restaurant to discuss our project. She only had ½ hour, so we quickly ran through our list of questions.

• organic straw, she would love to work with it, but hasn’t yet, hard to find, she prefers 2 string
• she will work $/hour as a consultant or GC, whatever we need, shift along the way is OK
• she is OK with our 2 year design time, she plans to be away for 2 months in the winters by then, so we need to plan around that
• her crew uses Vectorworks CAD
• she has her construction details on paper only and says they are constantly being updated because the state of the art keeps changing
  
• her crew does electric, paint and carpentry, plaster, subs out remainder and has an A-team of people in mind
• her subs have a good long-term relationship and work together well.
• her crew has what she says is "a great earth plaster guy"
• Pat Split and Sharron Block are title 24 people Michele said I should talk to
• She had reclaimed/recycled timber stamped on site for structural reuse or uses sustainably harvested lumber. Issues with reclaimed are knots and straightness. Can increase cost of labor because the crew takes more time to deal with these issues.
• her crew works time & material
• she builds post & beam frame
• 2 story home will cost more to meet the engineering requirements, X bracing etc.
• a 6” wall allowance has precedent in the county and doorways and window seats do not count. There is a new person in the county that she will talk to about posture towards strawbale before we commit.
  

1/27/07: I tested our well water with pool test strips. It's mid range hard, and the pH is near 7. I took a sample and mailed to a system provider at Home Depot for free testing and likely marketing materials for water systems. I never received results.

Catching up to the 21st century, part 7...permaculture & more home design

6-6-06
Cindy picked up a permaculture book at the library. Heavy stuff…it includes just about every progressive idea I’ve read about on all relevant issues: social, economic, agriculture, politics. My biggest take away so far is the idea of damming water and using it to gain more yield from a site rather than letting it drain off the site unused. In Santa Cruz, for example, the water could get harvested from the roof into a little pond near the home, then overflow in winter into a larger pond near the road at the western border of the site. Or, just have one pond for all water. The idea is that enough water is saved from winter rain to water the garden all summer until fall rains set in. Don’t let water run off the property without storing it for useful purpose - this would increase entropy! Get something out of the water. Plant a variety of shrubs and trees on the northeastern slope to make it more stable against landslide, get some nuts and fruits out of the deal, and create habitat for wildlife.

We have been talking about ducks. They hunt slugs and are natural habitants of a pond. The 2 could go well together. Same with coy. The pond could be an ideal final step in processing gray water after initial treatment in a constructed wetland.

Talked with Cindy about hands on natural building. She is not interested in talking classes. She just wants to be a worker bee taking direction, just like her gardening desires. I am interested in taking an extensive applied permaculture course. Need to read more and think about this.

6-8-06
Did a little research on Cor-ten. It comes in corrugated and standing seam forms. There is a distributor in norcal.

7-20-06 to 7-25-06
During tour 3 as volunteer rangers in the Alps (North Fork), Cindy and I came to the conclusion that a lofted pair of bedrooms on a 2nd floor would be the best compromise to reduce our floorplan but still provide a desirable space. Three visits to our friend's home in Ukiah let the concept of the loft and cathedral ceilings sink in. Cindy came with on the last visit and jumped all over the loft idea. I think this design with a 30’ wide floorplan may save Big Oak. A 30’x28’ first floor (840 sq-ft) is near square and has the best aspect ratio for thermal loss. Hopefully there is still enough room for up to 12% window area on the S wall to capture solar insolation. Some aspects of the design: approx 9x11 studio, full bath, kitchen, entry/pantry, great room and office nook on first floor, 2 symmetric bedrooms and closets in the loft. Approx 18’ cathedral ceiling peaking right above railing of loft. Approx 6’ ceiling on north wall of loft, 8’ on south wall of first floor. Close to 30 degree pitch on south roof face for optimum annual solar gain (assumes net metered). Either a very steep pitch stairway or spiral staircase to loft. Under and behind the stairs would be the library/office nook with built in bookshelves. Timber frame structure with strawbale or straw/clayslip infill. Adobe floor.

I ran HEED calculations on this design and although preliminary results show more electric heating required than a single story design, the increase is manageable. Operable thermal shades are an “ace in the hole” that can be used to reduce heat loss at night and should be incorporated. In fact, the use of these shades may allow for increasing the window area on the south face closer to 12% while maintaining the heat during the nights and decreasing the required radiant electric heating. ***The new version of HEED now has water heating incorporated. This allows better approximation of annual water heating needs by comparing summer usage to HEED’s summer usage. By multiplying the ratio of these 2 values by HEED’s annual usage, you arrive at your approximate usage. HEED assumes local average values for groundwater temperature. Our usage would be less than this when using solar water heating, but it is better to be a little conservative here than to shoot in the dark. The solar fraction calculator from Go Solar California (or similar tools for your local area) can be used to estimate how much of the water heating energy is replaced by various solar water heating systems.

Experts needed in our green home design: permaculture (me/us), tree, foundation, timber frame, plumber, roofer, strawbale, electrician , earth/lime plasters, adobe floors, finish carpentry.

Some thoughts on water. Harvest rainwater from the roof into a small pond near the house and above the elevation of the garden. The problem is that this amount of water would likely be gone before the rainless summer is over. A possible solution is to have a larger pond to collect land runoff. Could ultimately have a creek running down to a larger pond (near the road). The larger pond collects land runoff and neighbor’s roof runoff. A pump moves water from the large pond up to the small pond where it overflows via a little waterfall into the creek. This aerates the water and creates a unique habitat. Upper pond is used to water the garden by gravity feed off of a timer. The only downside I can think of is evaporation. However, evaporation is a natural characteristic of water features and will help create a unique microclimate.

Sept 16 to 29, 2006: OAEC permaculture class! I already posted about this class, but I need to say once again that it was a life changing experience for me. If you are interested in committing 2 weeks to a permaculture course, than I can't recommend highly enough the OAEC offerings.