beausoleil architects

Now we’re cooking with … not gas!

In many parts of the world, for instance sub-Saharan Africa, rural India, the desert parts of latin America and even in China, there is a push to use solar cooking to reduce the amount of wood and charcoal burning, to reduce local environmental air pollution and to increase public safety. Wood gatherers, often children and women, are more prone to attack as they range further from their home base in search of scarce resources. Large stretches of the world are being deforested, in part, by people needing fuel for cooking.

My daughter is going to Senegal in West Africa this summer, on a service trip with her school to help build a rural school.  I thought it might be useful to bring a prototype solar cooker to gauge its social acceptability and to test it in the local environmental conditions. I decided the cooker would have to be:

• Useful for local culinary customs, which involve cooking grain porridges, boiling vegetables, roasting meat, possibly baking bread.
•  Made of cheap (for my budget and theirs), easily repairable, replaceable, and sustainable materials.
•  Effective during the long, hot dry season (roughly eight months of the year)
•  Easily transportable, i.e., light in weight, foldable, durable
•  Hopefully, capable of being mass produced cheaply, if found to be useful and effective.

Solar cooking is simple from a scientific point of view, and also quite intuitive, as anyone knows who has gotten into a hot car on a sunny day. Incoming solar radiation at sea level embodies as much as 100 Watts of power per square foot, mostly in the form of visible light. If the light is absorbed by a dark surface, the surface will heat up, and the heat will tend to be radiated away as thermal radiation. If the surface is surrounded by glass, however, which is largely transparent to light but largely opaque to thermal radiation, then the heat is trapped – this is known as the greenhouse effect.  Using mirrors or lenses, more solar energy can be focused on a small area, increasing the temperature.  Increase the heat enough, and you have a cooker.

My design was based in part from what materials I found readily, and what my tools and crafting abilities were capable of. The design also evolved with step-by-step experimentation. I determined early on that the cooker needed to incorporate a glass shell so as to use the greenhouse effect.  I was able to find an inexpensive, cylindrical glass vase to use as my shell; it’s shape determined that I would create an oven rather than a ‘stovetop’ style cooker.

The design I settled upon had a parabolic reflector wrapped around the cylinder, held in place with a structural frame made of thin sheets that could be knocked down for ease of transportation. The prototype used cardboard, with Masonite or a similar artificial wood panel in mind for a final version. The pieces knock down to a (mostly) flat bundle, small enough to fit within the length and width of a typical suitcase.

The absorber plate which lined the inside of the glass cyliner was galvanized sheet metal with barbecue grade flat black paint as the finish. Some hemp rope, scavenged from the garage, was used for gaskets. Some quick experimentation with aluminum foil and cookie sheets as reflectors convinced me to use real mirrors – true specular reflectors seemed to be called for.

The first test of the prototype reached a temperature of 235 degrees – not great but good enough to bake cookies.  Then disaster: I was showing the cooker off on Earthday and the wind blew it over and broke it into shards…Oh, well, scientific progress goes boink. It was only a prototype, and proved to be less effective than desired, besides being too fragile, and probably too expensive.  It was lovely piece of design, but back to the drawing board!
 
My Challenge to my readers:

Create your own solar cooker – an oven or a boiler
Research local conditions, cooking practices and culture in your target area
Study the science of visible and thermal energy, absorption, transmission, radiation, insulation, and cooking
Design a beautiful cooker
Make a prototype
Test your ideas and your design
Do it again until you get it right
Take it out and try it in the real life
Manufacture it locally, and help transform the economy

Have Fun and Change the World

Rags to Riches

This is hopefully the first installment of a rags to riches story: how discarded water from your laundry (that’s the rags part) can turn into edible riches.

The San Francisco Public Utilities Commission is launching a new Laundry to Landscape pilot program, the object of which is to install greywater systems that utilize laundry wastewater for irrigating landscaping, thus reducing water and sewer use. The program is aimed at single and duplex home owners, and includes a short training class and subsidised sale of the necessary piping equipment.

For those not familiar with Greywater systems, they involve the use of wastewater from bathroom sinks, showers, bathtubs and laundries to irrigate landscaping (and in some cases for toilet flushing).  Wastewater from toilets, utility sinks and kitchen sinks are not included, as they contain much more bacterial and chemical components and need more sophisticated treatment.  Bathroom sinks, laundries, showers and tubs, given the use of appropriate cleansers, are considered safe for use in landscaping, as long as some basic precautions are taken with how the water is distributed.  The state has even legalized ‘simple’ systems, involving water from a laundry, without needing a permit. More complex systems are also possible, however.  Check out the Greywater Alliance or Greywater Action for general information.

The program is being run by the Urban Farmer Store of San Francisco, and they are looking for 150 volunteers for the pilot.  The benefits include a $95.00 subsidy on parts and training by experts. This will cover most of the costs for many people.

We intend to irrigate edible plants -- a small fruit orchard and blueberry bushes – with our system. It may take a few years for things to mature (growing edible plants in San Francisco’s climate is always a challenge!) but we have hopes for a cornucopia. 

V is for Victory (and Ventilation)

I recently attended another of PG&E’s great series of classes at their Energy Center, this one about ventilation in houses.  The Title 24 building codes regulating energy use in buildings changed this year (see previous blog “2010 title 24 energy updates”).  This class was about the ventilation component of these upgrades, which now require whole house ventilation as a matter of course.

The interesting thing is, although we all think of the forced air heating and cooling systems in our houses as ‘ventilation’ systems, most don’t actually do any ventilation. The instructor, Judy Roberson,  characterized this as “Where’s the V in HVAC”, HVAC being the industry acronym for Heating, Ventilation and Air Conditioning.  She even has a collection of photos of  HVAC contractor advertising, all of which mentions heating and cooling, none of which mentions ventilation.

Ventilation is, specifically, the replacement of stale, odorous, humid air from inside a house with fresh air from outside, and most heating and cooling systems in houses specifically don’t do this – they instead recycle the air, heating and cooling it, but never replacing it.  Fresh air is generally left to the occupants opening windows, or whatever infiltration happens when the wind blows or when someone turns on an exhaust fan.

While these ventilation methods have worked historically, as we have tried to make our houses more energy efficient by sealing up gaps in the building envelope, houses are now having more problems with indoor air quality.  There is relatively little of the small drafts that used to keep houses fresh, so air is left in place, and lack of oxygen, humidity, chemical odors from construction materials, and even mold are becoming a problem. This is the situation which the new code changes are meant to address.

The code allows for several compliance methods: stale air can be either exhausted from the house (fresh air is made up via infiltration through the gaps in the building envelope), or supplied into the house, or some combination of the two.  The ventilation can be continuous at a low level, or, intermittent with higher amounts of ventilation.  So, as of last January, all new and most remodeled houses will need to have these ventilation systems, on a twenty four/seven/365 basis. The older, more conventional exhaust fans are also now mandatory, not optional, in kitchens, laundries and bathrooms.

The main points of the PG&E class included Judy’s bedrock opinion that continuous – not intermittent – ventilation was far better for achieving the desired effect.  It is both more effective (intermittent ventilation can only be worse, never better than continuous), more cost efficient (smaller fans, ducts, simpler controls) and less likely to be annoying to the residents (less noise, no on/off disturbance, less obtrusive air movement).

Incidentally, we are talking about small amounts of air.  The typical bathroom exhaust fan, exhausting 50 to 100 cubic feet per minute (CFM) provides enough ventilation capacity to meet the code for the average house. And in fact, that is what some builders are doing – simply providing a better quality, quieter fan in one bathroom that gets left on all the time.  While this can comply with the minimum standards of the code, and is cheap, there are better options.  Judy’s favorite system was a supply fan which served multiple rooms, particularly bedrooms, where we spend most of our time. 

The supply-type system gives you filtered air from a selected source (not just infiltrated air from anywhere), and positively pressurizes the house so that there is less chance of infiltration from 'dirtier' spaces like attics, crawlspaces and garages.   The electrical usage would generally cost twenty to thirty dollars per year – not too bad considering the positive indoor air quality advantages.  This is the other main point: the energy savings of having a ventilated but ‘tight’ home, which doesn’t leak the much larger quantities of energy that a leaky house does, are much more than the energy used in ventilation.  Thus the title of the class: Ventilate Right, Build Tight.

Stained or Art Glass...

 

Well, the silver lining in this recession is that having more free time on your hands can sometimes lead to time for creative artistic pursuits.  I started doing stained glass (or art glass as the preferred terminology since there is nothing "stained" about it) at MIT of all places, not as a regular credit class as part of my architectural curriculum (the only art class offered at the time in the entire school was life drawing), but through their Student Art Association.

There I learned the basics of the craft and made a nice little Christmas present for my Mom.  Over the years, I experimented on and off, not quite sure it was the artistic medium for me as it takes a lot of patience (which I am sometimes short of) and skill, as well as a good artistic sense for colors, textures and composition.    As I tend to cut myself regularly on sharp edges,  I often wondered if the flow of blood was an indication I should stop and find a different pursuit.  But then when I go to a glass shop I can hardly control myself.  Think of the young child in their first candy store.  The colors, textures, pure art within each simple piece of glass excite me so.  At least for now, with a little more time on my hands, I will follow that excitement and see where it leads!  (And besides, in one of those same glass shops, Dan a very experienced glass artist and teacher, has a box of band-aids right at the front as he admits to cutting himself multiple times in one day!)

This piece was inspired by my winter magnolia, which is the first thing to bloom in my garden every spring.  The Chinese poem talks of the hope this blossom brings, descended to the earth (from heaven) quietly with a wave of cold. (Thank you again, Lena, for the poem.)

I was rereading  Genesis this week - the ultimate work of creation.  If we are really made in God's image, then each of us has that creative spark, wonderfully unique in each of us, that so wants to explore and create.  Go do it!  You never know what you might discover about yourself!

For more images of my glass projects, including commissions, click here.

Water, water, down the drain

Turn on the shower and wait, wait, wait while fresh cold water goes down the drain until the hot water finally arrives.  Another waste of an increasingly precious resource.

It is often said that fresh water will be the oil of the 21st century, increasingly sought after by competing claimants, harder to obtain, and expensive. That annoying waste while waiting for hot water may account for as much as 10% of your home’s indoor water use.

Ever wonder how big hotels provide instant hot water? It turns out that most hotels continuously circulate hot water through a piping loop which connects to all of the plumbing fixtures and then returns to the water heater, so hot water is always close at hand.  A few years ago, as houses got larger, and as our wealth enabled us to layout houses for comfort more than efficiency, homes started to be equipped with these systems also. Unfortunately, though they save water, they waste quite a bit of energy.  First there’s the electric pump used to push the water around, then there is the constant heat loss as hot water flows through cooler spaces, so that the water heater has to cycle on more often. Piping insulation is mandatory on these systems, of course, but the bottom line is still a system that wastes energy or wastes water.

Another solution, increasingly in use for the last few years, is ‘demand’, also known as tankless or instant water heaters.  Instead of the conventional tank that heats fifty gallons of water at a time and stores it for later use, these heaters only operate when a fixture tap is opened and the water starts to flow.  They just heat the water being used immediately, doing so very quickly and reasonably efficiently. Ideally, they are installed close to the fixtures, so there is very little water waste, and they sometimes only serve a few fixtures.  A typical house might have two or three of them, especially if the bathrooms are far flung. Both gas and electric versions are available. The down side of these units is their cost – both for the heaters themselves and for the large gas or electric services they need, and also for the high temperature flues the gas versions need. For a thorough discussion of the subject see the online consumer information.

But what can the vast majority of us do, who have conventional water heaters and an existing piping system, fully concealed within the walls and ceilings of our homes? Some ingenious person figured out a very simple, efficient approach that is both water and energy efficient.  This system, called an open loop, connects the existing cold and hot water supply lines at the most remote fixture from the water heater to create an artificial loop system.  The only new components are a small electric pump, a pushbutton, a thermostatic sensor, and an electric valve.

Here’s how it works: A few seconds before you need hot water (maybe you have entered the bathroom to shower and are about to disrobe) you push a button by the sink. The button activates the pump, which is generally hidden in the base cabinet under the sink, and which is connected to the hot and cold water lines which serve the sink. Water from the hot water pipe is pumped into the cold water line, where it returns to the hot water tank, reversing the usual flow direction. When hot water arrives, the thermostat shuts off the pump.  Now you have hot water at the sink, without having spilled a drop and having used the pump for just a minute.  In most bathrooms the branch pipe which serves the shower is only a few feet from the main pipe that now has hot water, so the shower will get hot almost immediately.

Depending on the layout of your house, one pump station at the fixture furthest from the water heater may be sufficient, or you might need two or more if the piping system runs off in all directions. In any case, very little water is wasted and the pump is only running a few minutes per day.

A couple of manufactures make pump and control systems designed for this purpose. The product line which looks the most interesting to me is the ACT,Inc. Metlund “D’MAND” .  All of the components of the system are included and it looks easy to install. There are three pump sizes available and three control system choices: a push button, a motion sensor (the pump would start anytime motion was sensed – possibly not the best idea) and for those who are technology addicts, a remote control. The most difficult part of most installations, one imagines, is getting a power source to the location where you want to locate the pump. List price of the basic unit is $339.50. We plan to order one of these and will let you know how our installation goes.

Another manufacturer to look into is Chilipepper . Their unit has a bigger pump than the D'MAND systems, which presumably translates into quicker hot water, but also reportedly makes for a much noiser unit.  It is also cheaper, at $179.99, but to me silence is golden.  Laing Inc.also makes good circulation pumps but they don't seem to have a unified system.

Please let us know if you have any experiences with these systems - we would love to share the information.