Green Business Spotlight: Energy

From time to time, the Editors of Green Architecture Notes turn the spotlight on businesses where sustainable products or technologies have been implemented in a move toward a more environmentally-conscious practice. Mueller Nicholls, a General Contractor and Cabinet Shop in Oakland, California, is one such business which is leading by example through a pioneering effort to reduce their reliance on fossil fuels.

Solar panels atop the Mueller Nicholls Builders' cabinet shop

A general contractor and cabinet shop will typically use a significant amount of energy for several functions, most notably for running portable and stationary tools, powering computers, illuminating facilities, and shuttling workers and materials to and from jobsites.  At Mueller Nicholls, we’ve long focused on making our operations more sustainable, and recently, we’ve concentrated on greening up two conspicuous sources of energy demands in our business.  In the spirit of inspiring other companies to do the same, we wish to share some key points from our experiences investing in alternate and green sources of energy to run the shop and office as well as some of our company vehicles.

 The cabinet side of the Mueller Nicholls’ business uses roughly 10,000 KW of electricity every month.  We’ve been eying the sun for quite some time as a potential power source, and in the summer of 2008, we took the plunge and installed a complete photovoltaic solar system.  The system generates 90% of yearly energy needs; we’re thrilled to have cut our dependency on less renewable sources of energy by such a large margin.


Although we focused on the sustainable concerns when installing the systems, financial considerations also came into play.  At that time, the federal tax credits were substantial and just about to expire.  We determined that the payback period would be a brief eight years (we’re 25% there!), and the idea of the monthly payments going to a local bank as opposed to a large utility was attractive.  For the PV system, the monthly cost of financing roughly equals the monthly power bill prior to installation of the system. Mueller Nicholls’ location in West Oakland made the logistical considerations very easy.  We have 250 panels that fit easily on the 16,000 square foot flat roof of the cabinet shop and also plenty of space for the inverters at the electrical panels.  The entire crew is aware that we’re getting our energy from the sun, which is a source of pride for green-minded employees.

With regards to our transportation, in 2006 we began replacing our standard SUVs and sedans in order to upgrade to hybrid vehicles.  Having company cars at the office allows a large number of employees to bike to work – sometimes up to seven employees out of twenty-two – and then to share the cars as necessary.  At this point in time, there are four hybrid company vehicles and our fleet gas consumption has decreased by roughly 1,300 gallons per year.  At $3.00/gallon, this saves $3,900 per year in fuel costs.



One of the four hybrid vehicles in the Mueller Nicholls fleet

When we purchased these cars, electric cars were less than practical from many standpoints.  Hopefully by the time we need to retire this fleet, we’ll be able to switch to electric cars.  We also have two diesel delivery trucks, which we plan to convert to bio-diesel as this option becomes financially feasible.  We look forward to the day when we can expand our PV system in order to charge electric vehicles and have portable PV solar panels as a way to provide power to a job site.

While our journey towards using more renewable energy sources for our power consumption is far from over, we’re pleased to have taken these first steps.  In a marketplace flooded with companies that tout their sustainable practices, we believe it’s crucial to put our money where our mouth is and to reduce the impact that our cabinet and construction practices have on the planet.

Jill Moran is a construction professional with 20 years of varied experience in high-end residential remodeling. Her recent entry into motherhood, timed precisely with the downturn in the local construction industry, has resulted in a slight re-engineering of her career.  She currently works closely with the management team at Mueller Nicholls, with an emphasis on communicating to the world at large about residential remodeling.

Fly Ash in Concrete

Slag pile in front of concrete batch plant

There has been a lot of discussion recently about fly ash in concrete as there are concerns about heavy metals in this by-product of coal fired power production. 

“Replacing Portland cement is a high priority for all of us…” Russell Perry, Smith Group.

 “The Environmental Building News” (Alex Wilson) continues to support the use of coal fly ash in building materials as long as:

a)      the use of fly ash reduces greenhouse gas emissions elsewhere in the materials stream; and

b)      the fly ash is chemically or physically locked up so that the risk of leaching is kept acceptably low.

Slag is a byproduct of steel smelting

A 2008 study by researchers at The Ohio State University found that fly ash concrete exposed to heat through steam curing retained 99% of its mercury content and showed final emissions similar to those of common soil.

A follow up study at Ohio State in 2009 that looked at both gas emissions and liquid leaching showed that the amount of mercury emitted from fly ash concrete was independent of the amount of mercury in the cement.

In California and much of the Western United States, the primary cement substitute in concrete is slag.  Bode concrete, for example, advertises a “green” mix that is 30% slag and 15% flay ash, in place of 45% of Portland Cement. 

Molecular structure and relative scale of concrete additives

Slag is byproduct of the metal smelting process.  Common components of slag include the oxides of silicon, aluminum, and magnesium, as well as sulfur, which is always present. Slag also contains phosphorous, calcium, ash, remnants of flux materials such as limestone, and remainders of chemical reactions between the metal and the furnace lining.  Slag cement has actually been used in concrete projects in the United States for over a century. The earliest use of slag cement was documented in 1774, when it was combined with slaked lime and used as a mortar. Slag cement was first used commercially in Germany in the 1860s, and it was such a success that engineers in 1889 decided to build the Paris underground metro using slag-lime cement.

Ross Levy, principal of LSarc in San Francisco, is dedicated to progressive, sustainable design and is a Contributor to Green Architecture Notes.  For more information, please see Ross’s bio on the Contributors page.

Designing Living Roofs – Part 2

Entry Walk towards House Ocho. Photo by Paul Dyer.

I’ve had several reasons for designing living roofs and have faced many challenges in implementation. Luckily living roofs can come in many forms and serve many purposes. In this post, I will try to briefly walk you through the second of my forays into this exciting and challenging subject.

For our House Ocho project in Carmel Valley, there were many reasons that we decided to design a living roof. Among those reasons, thermal properties, habitat conservation and fire protection were all important. But the driving reasons were visual. Placing meadow grasses and wildflowers on top of the buildings allowed us to insert our program into the stunning natural site that straddled a grove of costal live oaks and a steep meadow with far less visual impact. Because the house is sunk into the steep hillside and is approached from above, its roofs rather than any facade create one’s initial impressions of the house.

View of Roof and Skylights. Photo by JD Peterson.

Most of the downhill sides of the house are glazed windows and doors, and because of the seismic activity in the area, we needed to minimize the extra roof loads that deep soil would create. However, we wanted to create a roof garden that had the feel of a native meadow so that the house would blend in with the adjacent landscape.

We worked closely with Paul Kephart of Rana Creek to design the whole roof system. Paul has decades of experience designing living roofs and is responsible for, among many other projects, Post Ranch Inn, The Gap Building in Daily City, and Renzo Piano’s new Academy of Sciences in San Francisco’s Golden Gate Park. For House Ocho, we settled on using six inches of a lightweight soil mix that contained pumas to reduce its weight. We also used a water retention layer that holds a portion of the water in small cups and keeps the soil moist. This basically allows a shallow depth of medium to support plants in a way that is comparable to deeper soil. For plants, Rana Creek worked closely with our landscape designer, Loretta Gargan, and we ended up with a mix of native grasses and wildflowers, as well as strawberry and yarrow. See below for specific planting mix as well as roofing specs.

House Ocho in the Landscape. Photo by JD Peterson.

House Ocho:

Intentions: mostly visual, but also habitat and fire protection

Challenges: structural, waterproofing

Solution: American Hydrotech, 6″ of soil, complex mix of native grasses, wild-flowers, and strawberries


The waterproofing membrane is American Hydrotech MM6125 followed by a Hydroflex30 Protection Course and Root Stop WSF40.

The Drainage system is Floradrain FD40 underneath the growing medium layer and ¾” to ½” gravel with perforated pipe and surface drains at the roof’s edges.

Detail of Roof. Photo by Feldman Architecture.

The perennial plant species selected for the roof like Sand Sedge, Pt. Joe Fescue, Yarrow and Wild Strawberry are typical of the Oak Woodland understory and representative of the Monterey Peninsula region flora.

A host of annual wildflowers were over seeded in the fall and by springtime tidy tips, lupine, poppies, and goldfields surprised the owners with a colorful spring bloom. These annuals continue to sprout and flower each spring.

Jonathan Feldman is Editorial Director of Green Architecture Notes and Principal of Feldman Architecture.

View of the house and roof from the entry path. Photo by Feldman Architecture.

View of roofs from top of entry stair. Photo by JD Peterson.

View across the roofs. Photo by Paul Dyer.

View of roof from meadow. Photo by Feldman Architecture.

Front path and house at dawn. Photo by Paul Dyer.


Designing Living Roofs – Part 1

Rooftop Garden over Garage

I’ve been exploring various aspects of living or green roofs since I first started my own architectural practice about ten years ago. In fact my very first project was to fix up a shingled Victorian in San Francisco. It had a tiny garage in front of the house dating back to 1912 and a nice garden that wrapped around the garage. Wanting to expand the garage to fit two cars and occupy the entire footprint where the garden stood, I decided to make the roof of the new garage a giant planter. 

House before renovation

There have been many reasons which led to planting rooftop gardens over the years. In this first project, I valued having a nice green space in the tiny urban lot. I also felt strongly pushed to design in a way that begins to counter the urban heat island effect resulting from the over-paving of our denser developed areas. San Francisco also suffers from a rare policy that requires all roof water to be diverted into our sewers and then treated in sewage treatment plants – an extremely energy-intensive process. When we plant gardens on roofs, much of the rainwater is taken into the garden where it feeds the plants, evaporates into the air or, if designed properly, recharges the city’s ground water. 

Concrete planting structure before waterproofing

Placing what is essentially a large planter on top of a building is inherently challenging. Water is heavy and we must design a structure that can support the weight of a fully saturated planting medium and which will protect from any lateral wind or seismic loads that might occur during a deluge. Protecting against plant roots as they try to work a way through waterproofing is also a concern as is guarding against the sharp tools gardeners use which are not friendly to most roofing materials.

Plantings just after completion of construction

The first fix up project was a good first living roof project because I was only working over a garage and a little moisture seeping in above cars is much less problematic than similar leaks above living spaces. I essentially ended up building a concrete bunker in the side of a steep hill. This allowed me to have generous soil depth to accommodate large plants and their correspondingly large root structures. Typically, we are pushing to minimize soil depth in order to reduce the structural requirements. Since the garage was holding up the existing hillside and the house above, we ended up with a sloped garden whose depth went from 18 inches in the front to about twelve feet deep at the rear. Subsequently, we could plant shrubs and even substantial trees. For waterproofing, we used a torch-down membrane and covered it up with a drainage mat and a root barrier. We filled the planter with a conventional planting soil that was sprayed on top of the garage with a gunite hose. The plants consisted of trees, bushes and a fast-growing iceplant that served to stabilize the sloping soil.

View of Plantings Above

In subsequent projects, I have had different reasons for designing and implementing living roofs, and have faced different challenges. I will follow-up with accounts of other green roof projects shortly. Stay tuned!

The garden after the 1st year and years later

Jonathan Feldman is Editorial Director of Green Architecture Notes and Principal of Feldman Architecture.

Cottage On The Green

cottage entranceMy wife, Cathy, and I really liked our one-story cottage near downtown Palo Alto, but the floor plan didn’t work for us at all. The most direct path to the backyard was through the master bedroom, and loving to backyard-entertain as we do, running through our bedroom with plates of meat headed to the grill quickly lost its appeal. Also, our house cost us a fortune to “heat,” and we still froze our keisters off every winter.

When we hired Drew Maran Construction (DMC) to execute the remodel, all we wanted was a beautiful, warm-modern house. We didn’t set out to be supremely green. But Drew’s level of knowledge, and his willingness to teach us about the ultimate outcomes of our choices, had a huge impact on the greenness of our project. As the remodel progressed, we began to consider “green” in every choice we made, and we’re glad we did. The house is warm, comfortable, and more beautiful that we could have imagined. We refused to compromise on design or aesthetics for the sake of being green, and in nearly every case we ended up with both!

The decision we agonized over most was finding a heating system that would work the best and be energy efficient. We went with hydronic heat, embedded in thin gypcrete poured on top of the subfloor, powered by a condensing boiler. This system was definitely more expensive up front, but it was hands-down the best decision we made. Our new house is wonderfully warm and comfortable. We’re heating a 65% larger house and our utility bills are about the same as they were. We’re planning to install solar photo voltaics, too, to reduce our energy usage and utility bills even more. We totally nailed that one in terms of both function and green.

Another big decision was to deconstruct the old house instead of demolishing it. Drew advised us that we could offset much of the additional cost of deconstruction by donating the saved materials, and taking a tax credit. He was right. Not only did the tax credit offset the deconstruction cost—but we kept a lot of material out of the landfill. In the final analysis, this green choice also saved us money.

We do have a few “woulda-shoulda-coulda’s.” We love our Blomberg windows, but we might have been able to go even more green there. Also, since our house is so well insulated, we probably should have installed a “heat recovery ventilation” system; condensation can be a problem in certain low-traffic spots during the winter.

That said, we’re absolutely thrilled with our home. The new layout works even better than we’d hoped. When the house won the Sustainable San Mateo 2010 Green Building Award, it was (organic) icing on the cake!

Bruce Schena is an inventor, entrepreneur, and engineer with multidisciplinary interests and experience spanning robotics, medicine, business, consumer product design, haptics, wood- and metal-working, modern sculpture, and architecture. Bruce has Bachelor and Masters degrees from MIT, and was the first to receive the Degree of Engineer in Product Design given by Stanford University. He holds 71 issued US patents with over 50 additional applications pending. Bruce has worked as a freelance design & engineering consultant in the San Francisco Bay Area and is currently one of two Engineering Fellows at Intuitive Surgical in Sunnyvale, California. His responsibilities include defining and inventing next-generation daVinci® surgical robot architectures and technologies.

Mahiga High School Rainwater Court

On the central plateau of Kenya, near the lush city of Nyeri, the windswept arid town of Mweiga stands in the shadow of Mount Kenya.  Locals diligently farm the land, but their livelihoods are beholden to an average of 6” of rain per year.  Despite the lack of water, the people have a thirst to provide their kids with a better life, and they recently organized to build their first local primary school.  With the support of the new town council, provincial leaders, financial support from the Nobelity Project, and design assistance from local architects, engineers, and Architecture for Humanity, the people of Mweiga are now constructing a secondary school, and a special multipurpose structure known as the Mahiga Hope High School Rainwater Court

When constructed, the Rainwater Court will provide a covered space for youth to engage in a variety of sports: basketball, volleyball, netball, football and badminton.  The space will also be open to community members for special events, movie nights, performances, and market days.  But above all, the expansive roof of the covered structure was conceived of and constructed to collect precious water for consumption and use.

The court covers 4,850 square feet, the soaring roof canopy that covers the court can collect an estimated 90,000 liters of water per year. When rainstorms occur, water immediately drains into two tanks, located at the down slope side of the roof.  In total, the tanks will hold up to 30,000 liters and is connected to a UV purification system that renders the water for potable use – to provide meals for primary and secondary school children, and to water plants and crops on site.  The roof also performs dual duties; an array of PV panels mounted on the roof will help generate enough electricity to light the facility at night for sporting events or community gatherings. 

The space is designed for flexibility and diverse programmatic uses.  Between the two storage tanks are storage spaces for sporting equipment and an elevated platform and backdrop to serve as a stage for performances, a surface to project movies, or a spectator area. It will be Mweiga’s first community meeting space and will serve as a covered farmers market. 

Perhaps the most important aspect of the project is that the project has been designed and constructed with daily input from the community.  Architecture for Humanity’s Design Fellow, Greg Elsner, lives in Mweiga and actively engages with the children, their families and local officials in Mweiga and Nyeri Province.  “Living with the community has been the most powerful part of the experience for me. The community design meetings were awesome; it’s really exciting to watch the community share their ideas, volunteer in full force, and truly take the pride and ownership in the project.”  The total design and construction process has taken a little over one year and the final project is estimated to be completed in August 2010.

Mahiga Hope High School hopes to embody the spirit and ambition that the community holds for its children.  Michael Jones, Project Manager for Architecture for Humanity, cannot underemphasize the community value of the project, “The site comes alive with community members at every opportunity to contribute.”  While the Rainwater Court is not a classroom specifically designed for academic achievement, its multipurpose nature intends to provide the resources necessary to empower the youth and extended community of Mweiga physically, spiritually and mentally, through the gift of water, the gift of sport, and the gift of community activity.

Elaine Uang currently works at Feldman Architecture and formerly worked with Architecture for Humanity where she had the good fortune to visit Mahiga High at the start of the project.