With a typical roof shedding hundreds of gallons of water in a major rainstorm, an important and potentially expensive issue arises in many San Francisco remodels: where does it all go?

Rainwater diversion can be a cost-effective and sustainable solution. In this post, we will walk you through the definition of rainwater diversion, its benefits, and the permitting issues and methods necessary for execution.

WHAT IS RAINWATER DIVERSION?

Rainwater diversion is any method for managing storm water that keeps it from entering the sewer system. Water can be channeled into the surface landscape or a catchment system for re-use in other forms. (We will talk about catchment in Part 2 of this series).

SAN FRANCISCO REMODELING CHALLENGE

Unlike nearby municipalities where storm water runs into the bay, San Francisco homeowners are required to connect their storm drains to the sewer main. But just as water runs down to the sewer main, gases also rise from it. The transfer looks like this:

RAINWATER

Rainfall > Roof gutters > Downspouts > Sewer main

SEWER GAS

Sewer main > Downspouts > Roof gutters > Atmosphere

As long as the gutters are above the line of all windows, there isn’t a problem. However, room additions sometimes place operable windows in the line of fire. This is exactly what happened in our recent project at Sea View Terrace in San Francisco.

WHY RAINWATER DIVERSION?

Because we built out the attic and added dormers above the line of the existing roof gutters, we had a problem on our hands. The sewer main’s gasses would rise through the downspouts and straight into the dormer windows. Rainwater diversion was the most cost-effective option in this case, saving the homeowner thousands of dollars in alternative construction methods.

SF PLUMBING DEPARTMENT

There’s an easy formula for calculating the volume of rainwater your roof will shed.

With 1 inch of rainfall, 100 square feet of roof will collect 100 gallons of water.

As our case study has a 1,800 square foot roof, a 1-inch rainstorm will generate 1,800 gallons of water. So where does all this water go?

In an urban environment, one can easily see why the plumbing department is concerned about this much water being shed onto the ground. There are potential risks of flooding one’s property, a neighbor’s property, or causing sinkholes and major erosion. In order to meet the code, an engineered solution must be devised and approved to effectively divert this volume of rainwater.

DIVERSION SAVES HOMEOWNER MONEY

In the case of our recent project at Sea View Terrace in San Francisco, we had 4 options for fixing the problem of rising sewer gases below an operable window.

1.  Put a P-trap and trap primer on every downspout (functioning like the pipe under your kitchen sink). This leaves a Rube Goldbergian contraption on multiple locations of the building’s exterior, which is very unsightly as seen in the image to the right.

2.  Run internal roof drains to eliminate unattractive external pipes. This option is only cost-effective in large remodels that change the roof pattern.

3.  Connect all down spouts to a dedicated sewer line and sewer lateral with a single vent pipe. In our Sea View Terrace residence, the city sewer lateral was 15 feet below the sidewalk, which meant for costly permitting and excavation.

4.  Divert all rainwater into dispersion swales or drywells, or collect them into cisterns for re-use.

In our Sea View Terrace case, a drywell as described in Option #4 was the most appropriate for the design of the home, budget, and coincidentally the most environmentally acceptable solution. The engineering, permitting, and installation costs were approximately 50% cheaper than a downspout sewer connection for this home, saving the homeowner significant dollars.

CALLING ON A SOILS ENGINEER

The city plumbing department does not want to be responsible for defining such systems, but it will approve an installed system designed by a geotechnical engineer (or soils engineer). Engineering Design & Construction was brought onto the project to calculate the rate of water absorption in the neighborhood, and based on this calculation, design a drywell to accommodate the storm water shedding form the Sea View Terrace roof.

 WHAT IS A DRYWELL?

A drywell is a cylindrical pit drilled into the ground to a diameter and depth defined by a soils engineer. A plastic tube is inserted, filled with gravel, and capped for safety. Storm water from the roof runs through underground pipes into the drywell and slowly drains into the ground.

With our rainwater diversion into a drywell, 1,800 gallons of storm water efficiently move from the rooftop all the way back into the landscape without risks of flooding or erosion. The homeowner saved significantly as compared to alternative construction methods and passed the San Francisco building codes with flying colors.

Stay tuned for Part II where we will discuss another method for handling storm water runoff: rainwater catchment.

 Design Team: Andrew Mann Architecture, Scott Lewis Landscape Architecture, Engineering Design & Construction.

A volunteer helps rehabilitate a yard during the Rebuilding Together prep day.

In the spirit of Earth Day and being good stewards of the environment, it is important to also remember to be good stewards of our community. Rebuilding Together San Francisco is a non-profit organization that connects volunteers with construction projects focusing on the rejuvenation of communities.  With projects ranging from single family homes to non-profit organizations and school facilities, the San Francisco chapter has helped over 1,000 houses and 250 facilities since its inception in 1989.  This coming Saturday, April 28th is National Rebuilding Together Day where chapters and volunteers from around the country will partake in making their communities a better place.

High school students designed and built this 'parklet' in San Francisco's Outter Mission neighborhood.

The good news is that being stewards of the environment and stewards of community revitalization are not mutually exclusive.  The Parklet movement in San Francisco is benefiting communities by adding public space along commercial corridors, while improving our environment by encouraging pedestrian and bicycling transportation over cars.  Out of Site, a local non-profit organization, brings the arts into public high schools.  This year the architecture students designed, permitted and built a parklet on Mission Street near Ocean Avenue – the first one constructed in the Outter Mission neighborhood where many of the students live.

During the ribbon cutting celebration on Friday, students and community leaders participated in a drum circle on their new parklet

Credit: Shane Curnyn

A few years later Matarozzi Pelsinger teamed up with architects Aidlin Darling to design and build their new space on 11th Street in the SOMA district of San Francisco.   The team transformed the 14,000 square foot building, originally the distribution warehouse for the Jackson Brewing Company in the early 1910’s, into a passively cooled LEED Gold Certified building housing offices and a restaurant.  Because the building is on the National Register of Historical Places, the City’s planning department required that the new building maintain the historical integrity of the corrugated façade.  In order to gain natural light and incorporate operable windows to the east and west, the building was clad with a new perforated zinc skin.   The corrugated zinc is perforated with holes ranging from 1/16” to 1” in diameter which allow light and air to pass through new aluminum windows hidden behind it.  This perforated siding does double duty as a shield for solar heat gain and as a breathable skin that enables cross-ventilation of the interior spaces.  Because the zinc skin is set in front of the windows, a pocket of tempered air is allowed to circulate inside.

The same double-skin passive cooling principal was used in the SF Federal Building.  That structure uses a building automation system to control the operation of windows above the 5th floor to allow the building to breathe through a perforated metal skin. Read more here.

San Francisco City College also incorporated a passive cooling system that uses a wind powered louver system in a central atrium and skylights in their newly completed Joint Use Academic Facility. Read more here.

As an added benefit, the Matarozzi Pelsinger Building’s zinc skin inadvertently complies with the new bird safety standards that were approved in San Francisco in 2011.  Read them here.

Doug Nomiyama, Director of Business Development, Matarozzi Pelsinger Builders Since joining Matarozzi Pelsinger Builders as a project manager, Doug has managed more than a dozen residential construction projects in San Francisco and Marin.  Before joining Matarozzi Pelsinger, he managed several high-end residential projects on the Peninsula—including the construction of a 1,500 SF wine cave in a Los Altos Hills hillside.  Doug spent the first twelve years of his career in building material procurement and sales roles for residential housing and commercial projects worldwide.  Doug is currently managing projects and leading the business development team at MatPel.

Doug holds a Bachelor of Arts from Stanford University.  He is a Certified Green Building Professional and enjoys teaching new tricks to his Australian Shepherd named Bloo.

Source Energy

It takes about three times as much source energy (this includes the energy needed to generate and distribute a fuel) to deliver electricity to a home compared to natural gas. This is because only about 1/3 of the fuel energy burned at the utility’s power plant actually reaches a home in the form of electricity. The rest is lost due to inefficiency at the power plant and over power lines. Therefore, an electric water heater that appears to be 50% “better” than a gas one (0.9 Energy Factor versus 0.6 Energy Factor) actually uses much more (source) energy than the gas water heater. It is for this reason that when performance modeling a new electric water heater for Title 24 compliance there is a significant penalty.

 
Storage Water Heaters

Storage water heaters range in size from 20 to 75 gallons (or larger) and are fueled by natural gas, propane, electricity, or oil. Because heat is lost through the flue (except in electric models) and through the walls of the storage tank, energy is consumed even when no hot water is being used. New energy-efficient gas-fired storage water heaters are a good cost-effective replacement option if there is an existing gas line in the home. With more insulation around the tank and one-way valves where pipes connect to the tank, standby heat loss is substantially reduced. Prices are dropping for promising new super-efficient “condensing” and “near-condensing” gas water heaters. With a condensing gas water heater, before the combustion gases are vented outside, the heat in those gases is captured and used to help heat the water in the tank. If there is no access to natural gas or propane, rather than choosing an electric storage water heater a homeowner may want to consider a heat pump water heater, which is more efficient, but also more expensive. Conventional electric storage gas water heaters will still comply with Title 24 standards when using the performance calculation method.

On-Demand Water Heaters
Today many people are choosing tankless (or instantaneous) gas water heaters. These are very compact and generally wall-hung. Their rated efficiency is higher than that of tank units, usually around 0.82. However, they can be very expensive to install in retrofit applications, requiring special ductwork and upsizing of gas lines. Before rushing out to buy an on-demand water heater be aware that they are not appropriate for every situation. Consider the water distribution system. If the hot water use-points in a home are relatively close together a tankless system may work well. In many homes, water use-points are widely spaced at opposite ends of the house. If this is the case, a single tankless system with long distances between the system and the points-of-use can create frustration. The user will have to wait through a long “slug” of cold water before receiving hot water. With regard to electric units, residential wiring generally will not support a tankless electric water heater with large enough capacity to serve multiple uses. An small electric “point-of-use” unit may be appropriate for some applications, such as a remote vanity or half-bath.

Heat Pump Water Heaters
The good news for electricity users is that heat pump water heaters are becoming more common. Heat pump water heaters take energy from the air to heat water. Compared to a standard electric resistance water heater, heat pump models are more efficient because the electricity is used for moving heat from one place to another rather than generating the heat directly. The heat source is outside air or air in the room where the unit is located. They are available with built-in water tanks called integral units, or as add-ons to existing hot water tanks. A heat pump water heater uses one-third to one-half as much electricity as a conventional electric storage water heater. Electric heat pump water heaters are very Title 24 friendly.

Indirect Water Heaters
If you use a boiler for space heating it may be feasible to install an indirect water heater. An indirect water heater uses a separate boiler as the heat source. Hot water is circulated from the boiler through a heat exchanger inside a well-insulated water heater tank. An indirect water heater is an excellent option because it eliminates the tremendous flue losses associated with gas-fired storage water heaters and the hassles and extra costs of tankless gas water heaters. These systems can be purchased in an integrated form, incorporating the boiler and water heater with controls, or as separate components.

 
Integrated Water Heaters
These combined units feature a powerful water heater that provides space heating as a supplemental end-use. Heated water from the water heater tank (or tankless unit) passes through a heat exchanger in a central handler to heat air which is then blown into the home’s duct system.

Solar Water Heaters
Solar water heaters can be a great investment because they offer a virtually cost-free and renewable energy source for one of the home’s top energy-users. But because the feasibility and benefits of a solar water heater depend on a number of variables including where you live, roof orientation, and how many people live in the house, it takes extra savvy to know what the costs and savings will be. The initial cost of a solar water heater is still much higher than other competing technologies, but if one can make the upfront investment (made easier by tax breaks and rebates), it can save 50–75% of the water heating energy over the long term.

Michael Kunz is a Certified Energy Plans Examiner (CEPE) and owner of Energy Performance Services, a company specializing in California Title 24 energy compliance.  For more information call (888)828-9488 or visit their websiteat http://www.title24express.com

However, sustainable lighting is more of a mindset than a simple effort to reduce watt consumption. It’s about challenging yourself to avoid wasting electricity.

The 100-watt frosted incandescent light bulb that is being phased out by is certainly less efficient than fluorescent and LED alternatives. But it’s important to remember the reason it’s not sustainable: Ninety percent of its energy is not used to create light at all; it’s released as heat. Therefore, we end up using even more electricity to offset the heat output. Sustainable lighting should do what it’s supposed to – create brilliant, beautiful light – without the waste.

The concept of using lighting controls to improve efficiency rarely enters the mainstream energy efficient lighting conversation. Rather, dimmers and other lighting controls are typically categorized as aesthetic additions.

Dimmers are inherently sustainable! They enable you reduce lighting levels to your needs, cutting out all unnecessary electricity. In fact, if each U.S. household installed one dimmer, it’s estimated we would reduce overall electricity costs by $230 million and cut down on CO2 emissions equivalent to that of 370,000 cars.

Last November, at the Washington Post’s Smart Energy conference, Lighting Science Group CTO Fred Maxik discussed the changes he predicts for lighting in the future related to communication through microprocessors. “It could be a light bulb that’s just so smart that it detects sunlight coming through the window [and] starts dimming until you get the lighting you desire,” he said.

It’s easy to become focused on light source when thinking about greening a home. However, sophisticated lighting controls and dimmers will play just as large of a role in the future of sustainable lighting.

Emily Widle is a marketing specialist and blogger for Pegasus Lighting. On the “Light Reading” blog, she covers news, tips, and trends related to the lighting industry. She recently helped launch a lighting sustainability campaign called A Greener Light in an effort to start a dialogue about efficient lighting in the U.S.

As the city grew around them, the Jacobses decided to move out to the country near Madison.  They rejected Wright’s first concept for their second home, however, mostly, as they expressed in letters written to him, out of fear of large energy bills from a too-large home with glass-enclosed  rooms with 13-foot high ceilings in the exposed country setting of the house.

Now this was a Wright-sized challenge.  He responded by adapting the same principles developed in Usonian I but this time expressly oriented to a passively solar heated and naturally cooled design , which he termed the “Solar Hemicycle” (also known as Jacobs II).  The house was constructed in 1946-48, and has been continually occupied since then.  In 2003 it was designated a National Historic Landmark building.

The Solar Hemicycle is semicircular in plan, featuring a single concave arc of fourteen-foot high glass spanning the two stories both vertically and horizontally, and opening southward to a circular sunken garden and the Wisconsin prairie beyond.  The north, east, and west sides are bermed up to the height of the clerestory windows on the second floor, protecting the house from cold winter north winds, while the sunken garden in front combines with the rear smooth berming to create am air pressure differential that deflects snow and wind up and away from the large south-facing windows.  (This author has personally experienced this remarkable phenomenon many times.)

The interior lower level features a concrete floor slab for direct absorption and conversion of the incoming radiant solar energy.  Imbedded within the floor is a radiant boiler-heated system for back-up heating that emulates and supplements the solar-warmed floor.  All interior walls are Wisconsin limestone, providing an irregular and enhanced mass surface area for thermal energy exchange and interior temperature stabilization.  There are no dividing walls throughout the entire width of the downstairs, allowing for air and heat distribution evenly throughout.

The second floor is a five-bedroom balcony, suspended from the roof joists and hence not requiring obstructing support from below.  The front of the balcony is pulled away from the south glazing by several feet, enabling the solar-heated air from below to rise up onto the second floor and into the bedrooms over the full balcony width.  The air return of this convective loop is completed by a large circular stairwell connecting the two floors.

Summer natural cooling is aided by the adequate shading overhangs over the south-facing glass, as well as by the massive external earth berming and interior exposed thermal mass.  Summer “stack effect” daytime ventilation and nocturnal cooling are promoted by the operable glass doors in the south façade and the continuous band of operable clerestory windows along the entire upper portion of the bedroom north walls.

The semicircular plan actually reduces the solar gain by about 8% in comparison with a straight south-facing plan, but the arc provides support for the north wall, reducing structural costs, while the bermed arc serves to channel cold winds around and away from the south glazing to reduce heat losses.  The semicircular shape also provides for a sense of room separations and even gives visual privacy as one moves along the arc through the interior undivided spaces.

The house was constructed originally according to the norm of the day, with single-pane windows and minimal insulation above the berm levels and in the ceiling.  In the 1980s a new owner replaced all single-pane with double-pane glass, re-roofed with exterior insulation, and installed thermal night curtains (all of which we may assume that Wright would have specified, had they been available at the time).

Careful energy-use records kept by the third (and still present) owners, combined with this author’s thermal load calculations, enabled a determination of the passive solar performance of the house.  The passive solar features provide an average 53% furnace energy saving (“solar savings fraction”) for the entire Wisconsin winter.  The monthly savings coincide very closely in percentage with the average available solar radiation (“percent sun”), suggesting that the house on the average gains heat on a sunny day in amount to that which is used over a 24-hour period.

This is a very successful and exemplary “climate responsive”passive energy design, now in its 63^rd year of operation.

*The material in this brief description is derived from three published articles by the author, as well as from many years of experiencing life in that house.  The first two articles are largely summarized in the third, although with lesser detail.

Frank Lloyd Wright and the “Solar Hemicycle”, Proceedings of the 14th National Passive Solar Conference, Denver, Colorado, M.J. Coleman, Ed., American Solar Society, Inc., 14, 3-17 (June, 1989);

Frank Lloyd Wright’s “Solar Hemicycle” Revisited:  Measured Performance Following Thermal Upgrading, Proceedings of the 17th National Passive Solar Conference, Cocoa Beach, Florida, 52-57 (1992); and

The “Solar Hemicycle” Revisited:  It’s Still Showing the Way, Wisconsin Academy Review, 39, No. 1, 33-37 (1992-93).

Dennis Hayes, founder of Earth Day 1970

I grew up with a great appreciation for the indigenous earth, stone and timber buildings of my native New Mexico and found inspiration in the local designers who were tapping-in to the native intelligence of these design traditions for their own work. Peter van Dresser, a local writer and experimenter, whose lifelong interest in technology and its application within the framework of ecological processes was experimenting with sun-powered dwellings built from local materials and informed by both climate and culture. At Los Alamos, Douglas Balcomb, a physicist turned solar designer, was leading cutting-edge research on digital methods to predict the optimal balance of glass, thermal mass, and insulation to produce low-energy “passive solar” buildings around the country. Architect Ed Mazria was applying these principles in some of the most interesting contemporary architecture in the region and illustrated these in a popular pattern book for passive solar design. In the work of these visionary designers I saw a career path and a role for place-responsive, sun-powered architecture in a renewable energy future.

La Vereda Compound, Mazria Associates Architects

A decade later fresh out of undergraduate school I had a summer internship at the Solar Energy Research Institute, a new national laboratory under the direction of Denis Hayes with the mission of developing knowledge and technology to transition the nation from fossil fuels to renewable energy. SERI researchers were actively working on a plan to satisfy 20% of our national appetite for energy from renewable sources by the year 2000. But 1981 was also “morning in America,” the first year of the Reagan administration, and the White House decided that such efforts were best left for the private sector to develop in response to market demand. SERI was stripped of much of its funding and Denis Hayes delivered a memorable resignation speech, criticizing this misguided, short-sighted approach.

When I came to Seattle four years ago and finally met Denis, he hinted at creating a paradigm-shifting, ultra green urban building in Seattle as both a prototype and living laboratory for buildings of the future. Since then, the University of Washington’s Integrated Design Lab has been part of a large collaborative effort to help realize his vision for a net-zero energy and water building designed to radically transform our expectations for buildings and their performance.

The Bullitt Center, the Miller Hull Partnership, Seattle

When Miller Hull’s design for the Bullitt Center was unveiled to the public last May, Denis Hayes reminding the audience of the litany of environment threats and remarked, “…if the world had 3 or 4 centuries to address today’s major challenges we would be right on track, we might even be a little ahead of schedule. But we don’t have any time at all. What we need right now are some major leap-frogs that are broadly occurring around the planet. At the risk of being provocative I don’t believe there is a single office building today in the United States that is truly designed for today’s environment, much less for tomorrow’s. So, we set out to build one. With, what I hope is going to turn out to be no hyperbole at all, we set out to build the greenest office building by far in the world. A building that per area of square foot inside will use 40% less energy than the next most efficient building currently out there. A building that’s flexible, resilient, sustainable, a building that its creators can still be proud of 250 years from now.”

At ground-breaking for the project on Capitol Hill last week, Denis articulated the hope that this building might be “… the harbinger of a new architectural era characterized by ultra efficiency, renewable resources, zero-toxic materials, integrated design that allows the same building components to serve multiple goals, and very, very long-term durability,” a building with a design life of 250 years.

Rob Peña is an Associate Professor in the Department of Architecture at the University of Washington where he teaches architectural design and building science and ecological design. As a building performance consultant with the UW Integrated Design Lab, Rob works regionally with architects on the development of high performance and net-zero energy buildings. He is currently working on a book about the design and construction of the Bullitt Center.

8 dwellings
145-151 Laurel St.
Northern Liberties, Philadelphia
2009

The first LEED for Homes Platinum duplex residences
in the U.S.A.

This eight unit residential project explores the highly efficient and architecturally latent potentials hidden within the traditional form of the Philadelphia “Row” home. The vertical rhythm, regularity yet diversity of this most prevalent residential urban typology was the primary source of inspiration for this experiment. Thin faces fronting both Laurel and Pollard Streets mask and blur conventional lines of demarcation between all eight duplex dwellings both vertically and horizontally. In the process, a degree of density yet expansiveness uncommon to the thin space of the urban duplex emerges.  The Philadelphia “Row” is by nature a long, thin slice of dense, sustainable, urban space, typically ‘light-deficient’ and insular at its core. Thin Flats questions this traditional ‘deficiency’ by spatially reconfiguring the relationship between the interior and its skin such that its ‘core’ is flooded with light and air. This skin also affords each room on the ‘periphery’ of the dwelling the ability to step outside, and yet remain within the skin.

SUSTAINABLE ELEMENTS:
- Third Party verification that each unit is a minimum 50% more energy efficient in cooling, and domestic hot water energy usage than required by code
- Solar Thermal panels to provide domestic hot water needs
- Planted ‘green’ roofs to decrease thermal heat gain, prolong roof life, assist in storm water management, and provide planted and habitable rooftop gardens with views of center city
- Rainwater harvesting cisterns beneath parking area for irrigation of yards / gardens
- Each unit includes a detailed Home Owner’s Manual outlining the specific features and systems that are offered in the home that make it a LEED Platinum project
- Low flow faucets and fixtures reduce water consumption by 50%
- Concrete containing a minimum of 25% recycled fly ash content
- Double pane, low E, argon filled, thermally broken, aluminum clad wood windows and doors
- Home automation technology by Colorado vNet – centralized and programmable lighting, heating, cooling, security, and audio/video entertainment system to maximize convenience and minimize energy use
- Grade 1 insulation package including foam sealing of all joints to minimize air infiltration and closed cell spray-in foam insulation in exterior walls
- Maximum use of sustainable framing materials
- Maximum use of locally sourced / manufactured materials
- Hydronic radiant in-floor heating system
- HVAC system designed to ACCA Manual recommendations
- HRV(Heat Recovery Ventilation) system- Insulated hot water supply pipes
- Low or no VOC (volatile organic compounds) emitting paints, adhesives, and sealants
- Located within one block of public transportation
- Electric car charging port with fully electric car optional

VOID: SURFACE: VEIL

The façade of Thin Flats is at once a surface and a void, blurring the limits of the units within. The façade of the lower units is pushed back from the sidewalk to accommodate circulation.  The separation also floods a ‘basement’ space with light, aids in solar shading and creates a veil from public view. Balconies on upper floors recess behind the surface of the veil to create opportunities for civic engagement within the thin space of the façade.

Mike McDonald is an award winning green builder and developer.  Prior to joining sustainable custom home builder and general contractor Ryan Associates, Mike was the first builder to complete three LEED® Platinum custom homes in Northern California with McDonald Construction & Development. Mike’s brothers, who operate as Onion Flats are the design and development team behind the Thin Flats project in Philadelphia.

LOST IN THE SHADOWS

For me, using LEDs as task lighting is still a developing technology. I am very happy with the lumen output that we are starting to see now, along with the color quality. I personally lean towards a warmer color tone that is close to that of incandescent (2700° Kelvin), but many others do prefer the slightly cooler color temperature like that of halogen (3000° Kelvin). Still others that are doing fine detail work, such as jewelry making, like to have a color temperature close to that of daylight (5000° Kelvin).

Where I am seeing room for improvement is how to deal with the creation of multiple shadowing when more than one LED source is used in a task light. Those fixtures on the market with a single source LED act like a single source incandescent or fluorescent. One source equals one shadow, which is what we have all grown up with what we are used to seeing. But a single source LED may not provide enough illumination for many people. When multiple light sources are used, as we are seeing in the LED task lights that are coming onto the market, you get a shadow image for each light source. The more individual LED diodes you have in a fixture the more shadowing you get as well. When reading a book or a magazine this really isn’t an issue, but if your hand, pen or pencil comes in between the light source and the work surface it can have a lot of disconcerting shadowing with which to contend.

Although I am not lighting fixture designer, per se, I think of myself as an informed consumer who is constantly testing what is available out there on the market. My suggestion to the task light designers is that when multiple LED sources are used then some sort of diffusion material, in the form of a lens, will help ameliorate the problem. As individual LED sources become stronger and only one source is used then shadowing no longer is an issue.
Many manufacturers of recessed LED fixtures have seen that that this multiple shadowing was an issue and have produced fixtures with an integral diffusion lens. It would be a good idea if the manufacturers of LED task lights would take a look at what the recessed LED fixture manufacturers are doing and see how they can incorporate the addition of a diffusion material into their products.

I still am a very strong advocate of using LED sources for task lighting. I would just like to see the next step in refinement; so that when people make the investment they are getting something that they can live happily with for the next 16 or 17 years. Since LEDs last for so darn long I want to make sure that my love will last.

Randall Whitehead is a frequent contributor to Green Architecture Notes.

The completed EcoCenter from the South East.

As a follow-up to a recent post on Heron’s Head EcoCenter, we caught up with Alex Rood of Fulcrum Structural Engineering to discuss his contributions to the project. For those who have not read our recent post on the project, Heron’s Head EcoCenter is San Francisco’s first off-the-grid educational facility and laboratory for sustainable design sponsored by the non-profit organization Literacy for Environmental Justice. A project 10-years in making, the EcoCenter was finally completed in 2010, and incorporates many innovative sustainable design features including solar panels (both PV and solar thermal), living roof, rainwater harvesting, greywater reuse, living machine on-site wastewater treatment, SIP panels, super green concrete mix, recycled building materials, passive design, and the list goes on.

Site/soil: Located on a former industrial landfill in Hunters Point neighborhood of San Francisco, Alex’s first challenge was to design the foundation system that could sit atop the soil with extremely poor bearing capacity. To overcome the less than favorable soil condition, he decided to utilize 10” mat slab but he also had to incorporate a series of troughs for the indoor constructed wetland into the slab/foundation design. The challenge did not end there. The soil condition was so poor that he was told to anticipate as much as 10” to 12” of settlement over time. This meant utilities that would typically be laid below the slab now had to be routed within concrete troughs formed into the slab until they exited the structure above grade to make service connections. To make matters worse, he found out that below the site is a clay layer of landfill cap designed to remediate the contaminated soil, but the exact depth of this cap layer could not be determined. He had to proceed with caution to ensure that the weight of the structure would not cause the cap layer to fracture. In addition to solving all of these engineering challenges, it was his job to provide a cost effective foundation design to fit the tight budget of the project.

Rebar prior to pouring of the concrete foundations.

Concrete: Almost every modern structure in the world uses concrete to varying extent. While its longevity makes it a good building material, the environmental footprint of cement production is something Alex wanted to tackle on this project. According to Alex, experts estimate that cement production contributes to about 7% of carbon dioxide emission from human source. He started by specifying a green concrete mix containing 50% slag for cement replacement but once the job broke ground, he collaborated with the concrete sub-contractor and the supplier, Bode Concrete, to push this green concrete mix further, ultimately ending up with 80% slag and 100% recycled course aggregate. In the end, not only was he able to use the greenest concrete mix he, or Bode Concrete, had ever heard of, but the builder was able to provide concrete that was superior to the original specification in many ways. It ended up exceeding the compressive strength requirement by two fold, the concrete showed no cracks and will provide superior protection against rebar corrosion, all thanks to its high slag content.

SIPs panels prior to sheathing

Framing: Once out of the ground, the remainder of the structure was designed using Structural Insulated Panels (SIP). Having worked on many other SIPs jobs with the project architect, Toby Long, Alex knew that Toby would want to use SIPs for the project for many of its environmental preferable attributes. There are always challenges in designing SIPs structures in seismically active zones, especially when the building is not a simple box but he was able to use his extensive experience with SIPs to help Toby realize his design. Being the first SIPs project for the builder and the framing crew, he worked very closely with the builder and was often asked to offer creative solutions to troubleshoot issues arising in the field. Thanks to the countless hours of research by the LEJ project manager Laurie Schoeman, SIPs panels made with FSC-certified OSB panels were sourced. All framing lumber used in the job to amend the SIPs system was also all FSC-certified.

We asked Alex what was the best part of the project for him.

The completed EcoCenter from the South East

It was the collaborative effort with the concrete sub-contractor, Gerald Creed of OSM Co. and the local concrete producer, Bill Garland of Bode Concrete. In fact, it was Gerald who initiated the idea of exploring an even greener concrete mix than the 50% cement replacement originally specified. Bill had worked with a concrete mix with 75% cement replacement, and he has also used crushed returned course concrete aggregate in non-structural flatworks. Not only did we decide to combine both of these ideas, but we also decided to use the mix for the structural slab/foundation, while increasing the slag content by additional 5%.

Alex believes it was the collective knowledge and will to do the right thing for the environment that allowed them to take the leap of faith to push the boundary of the green concrete mix. Everyone went above and beyond their call of duty to come up with the greenest concrete mix they have ever worked with.

Taisuke Ikegami is an architect working at Feldman Architecture and is a frequent contributor to Green Architecture Notes.