Designing a Sustainable House, A Geometry and Physics Honors Project By Michael Silverman and a Peer Natural resources, such as water, are finite and will become scarce. The way houses are now designed is not ecologically sustainable or beneficial to the environment. We want to find alternatives that benefit nature and the occupants at the same time. First, we have decided to maximize volume to surface area so our house takes longer to heat up and to cool down, making it easy to regulate and maintain the temperature inside. A simple and practical way to do this is by altering the standard box shaped house by rounding out corners into semi-circles, and by making the house one smooth shape, instead of having rooms protrude from the side walls. This keeps many of the walls between the rooms inside, which means less overall outside surface area for the sun to heat. Another way to help keep the inside at a regulated temperature is by using rammed earth for our walls. Rammed earth is cheap, environmentally neutral, and is a good insulator. Rammed earth is compacted earth combined with a concrete stabilizer. The use of thick rammed earth walls increases the walls’ thermal mass. The idea of thermal mass essentially describes the ratio between how thick an object is and how fast it heats and cools. Compare a sheet of paper to a stack of one hundred sheets of paper. If you put these two sets of paper under a heat lamp, the single sheet will become warm within a matter of seconds, as where the stack of papers will take considerably longer to heat up. Consider the application of this principle to home construction. A typical residential outside wall is about eight inches thick at most, and is made of plywood, chicken wire, and foam insulation. The wall we recommend for a sustainable home is two and a half feet (thirty inches) thick, and made of rammed earth. The thick, well-insulated walls will be an easy way to keep our house warm in the winter and cool in the summer because they don’t as readily transfer heat as conventional walls. We have also researched solar panels, and will be using solar panels as the primary power source for our house. We have decided that instead of using the conventional way of cooling solar panels we will liquid cool them by running water under them in pipes, which will absorb the heat the solar panels generate. This will be an efficient way to cool the solar panels because of water’s high specific heat capacity, which means it can absorb large amounts of energy. We will also use this already-heated water as our hot water supply, cutting down significantly on the cost of heating water in the summer months. We will also use super windows throughout our house to provide natural lighting. Taking advantage of natural lighting will reduce electricity usage. Super windows are doubled paned, letting in significantly less heat compared to conventional windows. Reducing the amount of electricity our house uses is an integral part of green building. Using Energy Star appliances to reduce power consumption is another good way to accomplish this. However, reducing electricity needs is not the only way energy can be reduced in the house. It is extremely important to reduce heat energy in the house. Easily three-fourths of the heat in your house comes from the outside environment, from opening doors or sunlight coming through the windows. Using super windows, as we have mentioned, is a great way to reduce this incoming heat. But heat also comes through walls. As the sun shines onto walls, it heats them up and then that heat is radiated into the house. Rammed earth helps reduce this heat intake; however, it does not completely eradicate it. In our house, to help reduce this heat intake we have changed the design. We have reduced west and east exposure of our house’s walls to decrease incoming sun in the early morning and late afternoon, when it shines most directly on walls. This was done by positioning the curved, semi-circular, sections of the house on an east-west orientation. Also, we have a three-foot overhang, or extension of the roof, to block sunlight from hitting our walls directly. This allows natural light to get in through windows but stops the sun from heating the walls. We have also “sunk” our house three feet into the ground, which is an inconspicuous way of decreasing its exposed surface area. Not only does this give a huge amount of thermal mass to the bottom three feet of our walls, but it also increases the effectiveness of the overhangs by ensuring they can shade the upper area of walls. By reducing the incoming heat energy from the outside, which is considerable in Phoenix, it will drastically cut down on heating and especially cooling costs. We will also reduce energy consumption by using LED’s throughout the house. LED lighting lasts longer and uses less energy than incandescent or florescent bulbs, and it has minimal heat discharge. It is not only important to reduce heat coming from the outside, but heat produced inside the home as well. The use of a smaller refrigerator and reduction of inside stove use in the summer help cut down on internal heat production. Using a solar oven to cook foods is an inexpensive alternative that can cook food like a slow cooker, and does not take any electricity at all. Temperatures inside solar ovens, on clear days, can reach up to 400 degrees (200 C) which is enough to boil water, cook food, and reheat food. By replacing much of the stove and oven use with a solar oven, we reduce the heat produced inside our house. Another ecological feature that we implemented in our house is a living machine. A living machine is a system that combines multiple tanks and thousands of bacteria, koi, goldfish, plants, water, algae, shrimp, snails, and microorganisms to clean mucky waste water into crystal clear water than can be reused as greywater in toilets and to water plants inside and out. This turns water that would otherwise go down the drain into useable, safe water. This method of waste water treatment is sustainable, chemical free, and odor free, besides the smell of the plants and flowers that grow because of it, it is also more fiscally responsible compared to traditional waste water treatment because it sustains itself. One may ask, “How can a simple system of tanks clean waste water (solid material included) into clean greywater that can be used over and over again for an entire household?” To learn more on how well these nature based systems can work, we looked at the town of South Burlington, Vermont. The residents filter and treat ten percent of the town’s sewage using living machines. The living machines work so well that when a large amount of gasoline came through the system at one point the system was able to survive the shock. I quote one of the students there, "All this gasoline came through and killed the plants in the first tank,” Olena Welhasch, a senior who has experimented with living machines, said, “The operators were really worried, but they had to keep the experiment running. The plants ended up regenerating after the gas passed through, and the following tanks were not affected. Nature has such a huge potential to self-organize and self-repair." Living machines are also used in various industrial complexes and companies around the world, including the Ben and Jerry's Ice Cream plant, the Body Shop bottling facility, and the M&M/Mars candy bar factory. Another example that living machines are the future and that they are incredibly efficient is what the class of 2000 at Penn State did as their class gift. They elected to restore one of the old greenhouses in the botany department into a living machine. The machine can handle up to 700 gallons of waste from 15 faculty and students who work there and from up to 50 to 100 visitors who pass through the old greenhouse. The machine can handle ammonia (from urine), solid excrement, toilet paper, soap, as well as chemicals that some careless student may have poured down the drain. The examples of South Burlington and Penn State’s experiences prove how well living machines work even on a scale many times larger than what we will have in our house. Our living machine will provide waste management for our house along with some beautiful ponds, flowers, and plants that our house’s inhabitants can enjoy throughout the year. Nature has demonstrated that she does indeed know best and all we have done in our project is allow her to do her job in harmony with a comfortable lifestyle for our house inhabitants. These are the steps we took in the building of our model and the process of researching, writing, and finishing our honors project. We have been meeting on Tuesdays and Thursdays since mid-November. We have worked from 1 to 1½ hours each meeting (3:40-4:30 or 5:00). More recently we have been meeting every day of the week and weekends as well, to build our model, finish our essay, and practice our presentation. The first couple of months we spent researching our topic and finding out information on sustainable development, green building, solar panels, and living machines. We also explored all of the links and leads Mrs. Walker gave us. As part of our research into green buildings, we went to Sears to look at the energy efficiency of the appliances. Some of the sales people were interested in what we were doing and tried to help us as much as they could. We started to build our model in the middle of March. We had been gathering supplies all along, but this was the time where we started to put it together. We first started discussing which aspects and green building techniques we wanted to use in our model. We then sketched out various designs. After a couple of drawings and much deliberating, we found a design we both agreed upon. We then made a sturdy base to build our model on and wired the bottom so that it would be easy to put in LEDs later on. We then started out by cutting the walls of our house and spray-painting them. After that, we started to work on building all of the furniture in our house. It took multiple tries to find the scale we were looking for on some of the furniture items and many trips to ACE and Joann’s for the supplies to build the furniture, but we are now satisfied with the results. All of the furniture in our house is custom made by us using balsa wood. All of the cloth and fabric you see on our model was cut, glued, and attached by us. We did not use store bought miniature items for any of it. The only exception to that are the lampshades. We found their size was perfect to our scale and we could not make them by ourselves out of balsa wood very easily. We used hot glue to stick it all together and we ordered LEDs for our house. In total we have used 48 LEDs in our house. To power all of those we used a computer power supply that Jacob’s brother, Paul, and we modified to work with our LEDs. The modification only involved some minor changes to the outside of the power supply, as in cutting out extra plastic and wires that we did not need. We found that a power supply was uniquely qualified to power large amounts of LEDS because the large amount of lighting we have used for our model would have taken a considerable amount of battery power to manage. We have also taken pictures along the way to show our progress. We will show these during our PowerPoint presentation. If you have any further questions, we would be happy to address them. Sources We received many contacts at the Green Building committee meeting and we followed up on most of them. We called or emailed the most relevant contacts and tried to get as much information out of our contacts as possible. Sometimes they were helpful; sometimes they were not. a. Another of our major sources so far has been the internet. It has been extremely helpful in providing us with information so far. Below is the list of links we have used to date and a one sentence summary of what each is about. i. www.nrel.com This is the National Renewable Energy Laboratory ii. http://www.unitednuclear.com/aerogel.htm This is the Aerogel website, an insulator that is 99.9% air. iii. http://images.businessweek.com/ss/05/12/china_wonders /index_01.htm This is an article on futuristic designs of buildings in Japan. iv. http://www.innovalight.com/index.html This is a website that details a type of silicon-based ink that can reflect light. v. http://www.bigfrogmountain.com/searchresults.cfm?Type =Solar%20Electric%20Panels# This is where we have gotten most of our information on solar panels, their power outputs, and prices. vi. http://newenergy.org/sesci/publications/pamphlets/photov oltaic.html This is the link that you gave us. Also a source for solar panel information. vii. http://www.rps.psu.edu/0009/machine.html