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

OCHO TECHNICAL INFO

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.

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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.

LED: The Tiniest Giants...

If you’re remodeling or building a home, you know that California has some of the toughest energy codes in the nation, and getting tougher every couple of years.  From a lighting perspective that means that lighting must be highly energy efficient.

The tiniest giant

Luckily, we have a tiny new player in the world of lighting: Solid State Lighting (SSL) better known as LED lighting. SSL has taken the lighting industry by storm and will soon knock out inefficient contenders such as incandescent, halogen and many fluorescent lamps by providing warm, dimmable, long lasting energy efficient light.

SSL is the best lighting innovation to come along since the Edison lamp, in fact, there is nothing on the horizon that can compete with this light source for the next 20 years, and SSL is projected to get better and better in 6 month cycles.

Why? Because SSL produce light via an extremely energy efficient  process called electroluminescence thereby eliminating the need to heat a filament in a gas filled vacuum tube like incandescents, or exciting gases in an arc chamber as in florescent lighting, both of which are inefficient ways to produce light.  

Instead, SSL only have to move electrons over a tiny distance to produce light. The LED chip itself is extremely small and requires very little energy to produce huge amounts of light.  Currently, a 1 watt LED is only about 1/8” square and can produce over 150 lumens per watt (LPW) of usable light.  By contrast, a 100W incandescent lamp only produces approximately 17 LPW, and fluorescents generate between 50-100 LPW – energy efficient, but still not as efficient as SSL.

This light source which until recently was considered too blue and too expensive for residential applications, now easily produces excellent color temperatures rivaling the purest white light from halogen lamps, outclasses any fluorescent light source, and is falling closer and closer to an acceptable price point.

When considering the cost of SSL, one must accept a paradigm shift in how you calculate lighting costs and its associated value. Historically, lighting cost was determined purely by the cost of the fixtures, and lamps were considered a disposable commodity.  With SSL lighting there are more criteria to consider: fixture cost, energy consumption, lamp efficacy, demand on cooling systems and lamp life. These parameters were given only marginal considerations by homeowners in the past, but going forward they will be given a bigger consideration especially since lighting is one of the highest energy consumers in the home.

SSL is not a disposal commodity; you can expect to use a typical SSL source for over 15 years. That’s longer than most people keep a car, or most appliances, so this product should be given the same consideration that one gives to choosing big ticket items such as flooring, appliances and surfaces.

From a green perspective, SSL are considered very environmentally friendly; in fact, they are environmentally friendly from production, through usable life, to disposal. 

Alfredo Zaparolli has over twenty five years experience in high-end residential construction, design and engineering. Alfredo established Techlinea Inc. in 1985 to provide quality lighting design services to discerning clients throughout the US and abroad. Prior to the founding of Techlinea, Alfredo was principal and partner of Electric Connection Inc., and was responsible for designing and installing electrical and lighting systems for many notable residences throughout the San Francisco Bay Area. He combines a deep understanding of lighting technology and design with a unique blend of creative vision, hands-on technical expertise, and collaborative style to make Techlinea sought out for projects worldwide.

Evaluating Green Choices In Sustainable Flooring...

FSC-certified Brazilian Cherry lumber at a sawmill in Brazil.

People often ask me to recommend the ‘greenest’ hardwood flooring option, expecting me to tell them to use reclaimed wood or Bamboo, and they’re shocked to hear my answer. After years of witnessing the impacts of our purchasing decisions on forests worldwide, I tell them to use FSC-certified tropical hardwood. Reclaimed wood and Bamboo are great environmental options – they both help reduce demand for wood harvested from forest ecosystems. But in my view the most significant positive environmental impact we can make is to support sustainable forestry in tropical countries.

The world’s tropical forests are rapidly disappearing – we lose an area roughly the size of Washington State every year. Logging certainly plays a role in some of that deforestation, especially when loggers cut roads into previously inaccessible areas, but the majority of the habitat destruction is for agriculture and cattle. The developing world often faces a ‘use it or lose it’ proposition – if we don’t create an economic value for the forest, it will be cleared for other purposes. So, whether it’s nuts, medicinal plants, or selectively felled timber, products that can be taken from the rainforest without destroying it are one of the best ways to breathe life into the lungs of the planet.

An aerial shot of an FSC-certified forest in the Amazon taken immediately after harvest.

The Peten, a jungle region in Guatemala, serves as a perfect example. The portion that was set aside for sustainable forestry under FSC guidelines enjoys a healthy in tact canopy, whereas the portion that was established as an ecological reserve is now a patchwork of slash and burn agriculture. The Guatemalan government doesn’t have the enforcement capacity to keep poor farmers out of the reserve, but where the forest is creating an income for local communities, they are out protecting the trees themselves. By buying FSC-certified wood from these communities, we create the economic incentive for them to keep the forest alive.

Of course, buying wood from half way around the world may seem like a poor environmental choice because of the transportation impacts, but taking a closer look at the carbon footprints of wood products reveals that things are much more complicated than many people assume. For example, a wood floor that is cut from a log harvested near a river in Brazil will travel primarily over water on its way to foreign markets. Because ocean freight is dramatically more efficient than trucking, it may actually take less diesel to get that Brazilian floor to its final destination in Seattle or New York than to truck an Oak floor to those locations from Wisconsin or Tennessee. Similarly, a Bamboo floor that is grown and manufactured close to the coast in China will have a substantially smaller carbon footprint when installed in L.A. or Miami than a Maple floor coming from Minnesota or Canada. And then there’s the fact that in today’s global market, Chinese factories are importing huge volumes of North American species, turning them into furniture, flooring and other products, and shipping them right back to towns not far from where the trees were harvested. Nowadays, to make an informed judgment about the real transportation impacts of a wood product, we may have to trace back through many legs of the journey.

Bamboo flooring installed in the Dahesh Museum in New York City.

To complicate things further, we can’t make the assumption that certain species are good and certain species are bad. Brazilian Cherry is a species that is biologically abundant throughout the Central and South America, so an argument could be made that using FSC-certified Brazilian Cherry might be better than using uncertified North American Walnut, which is in increasingly limited supply. Much of the White Oak that is currently being sold in the U.S. is coming from Chinese factories that buy illegally-logged material out of Siberia, from what is shaping up to be one of the greatest ecological catastrophes the world has ever seen. One would think that good old-fashioned White Oak wouldn’t be so risky.

So as with many questions in green building, the answers are fairly complicated. But one simple truth will always hold true – we are better off specifying a wood product that is certified under a credible forest certification system like FSC than simply winging it on our own, believing what our suppliers are telling us or relying on assumptions that in many cases don’t hold true. The more we can learn about where the product was harvested, how it was harvested, and the journey it took to the jobsite, the better, but often credible information is hard to come by. If you can take old wood from a building and re-use it in a project just up the street, I may have to re-visit my recommendation about the ‘greenest’ product available, but those opportunities are unfortunately rare. In the meantime, spec FSC, and take the bus if you can.

 

The author in a Bamboo plantation in Zhejiang Province, China.

Dan Harrington, former VP of Product Development at EcoTimber, has spent many years traveling the globe visiting factories and sustainable forestry operations. Dan serves on the Sierra Club’s Forest Certification Committee and formerly served on the USGBC’s Technical Advisory Group for Certified Wood. He is currently the Commercial Sales Manager for Golden State Flooring, an FSC-certified hardwood distributor based in San Francisco.

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