Solar and Harden Duplex

Renewable Generation!

2009-05-17T16:27:00.004-05:00

Hey all-

The solar electric system finally got fired up on Monday! Yes, we are now generating energy.

Brief System Description:

42 BP 4175 roof mounted modules, canted at 20 degrees, Rated Power 175 W
4 Romag custom overhang modules
Single insulated conductor MC USE-2 cables are used to connect the modules
There are 3 inverter groupings
Total System 7.8 kilowatt solar array
Grid-tied

As of Friday, we generated 129 kW. For those same five days we only used 97 kW for both homes. For the previous week, when the solar was not hooked up, we used175 kW for both homes.

I look forward to charting this data and will continue to share the information.

Thank you to all the volunteers who helped make this happen! Below are pictures of the system being turned on!

Visitors from Mexico

2009-03-14T13:23:00.005-05:00

On Friday, March 6th we had a wonderful group of students from a technical school in Mexico come visit our home. They will be participating in the 2010 International Solar Decathlon competition. Dason Whitsett, from the 2005 UT SNAP house team gave the students a tour of the home and provided first hand insight about the building design, mechanical systems, and overall experience.

The students really enjoyed the experience, as did I, since it was the first time a alumni of the SNAP house has been by to share their story. We welcome others!

Here are some images of that day.

Solar Water and PV Electrical Update- a bit of clarity

2009-03-14T12:57:00.003-05:00

It seems that there was a blurb in communication between us and BCDC about how the new hot water system will be working. According to Blackland, "The Harden House will continue to get heated water from the Solar House tank but will have a gas heater as backup if the water is too cool. In essence, the Solar House system will act to "pre-heat" the Harden House water."

There will be no shut off valves between the two units, like we indicated in the previous post and diagram. So, essentially the the flash heater (and its high usage of electric) is still part of the equation.

As far as connecting the Solar Electrical system working the latest news from BCDC is: "The PV panels need a final inspection which requires a plaque be placed on the solar meter box. Eric Kay has the data from Aaron Cloninger and is to get the plaque made soon. But he also needs to reinstate the electric permit that lapsed Feb. 1. With those done, we can hopefuly flip the switch."

Lessons Learned- Learning Lessons about the hot water system

2009-02-08T16:40:00.008-06:00

Well, this past week we had a wonderful meeting with the folks at Blackland about the hot water system. It was agreed amongst us all that the problems associated with the hot water system was our first "lesson learned" at the Solar Harden Duplex.

THE LESSON (Detailed in the previous post and summarized here)
Based on our data collection-that indicates high water usage (waste) at the Harden residence- and personal stories of lack of hot water (SNAP and Harden residents), Blackland has decided to install a gas powered hot water tank in the Harden house. This will allow the Harden tenants to readily get hot water without drawing it from our thermal hot water system. In addition, Adam and I will have one less meter to record and one less bill to reconfigure every month.

Even though the new tank will solve the current problem, we all agreed that during the summer, the original design of the solar thermal hot water system just might work. Therefore, we are going to create a hybrid system. I mean, do we really want to waste all that free solar energy? Especially since the SNAP house current solar thermal system is completely over sized for Adam and I; especially in the summer time.

THE HOT-WATER HYBRID SYSTEM
The new hybrid system will consist of all the existing components: Solar thermal evacuated tubes, the hot water tank, pump, and flash heater. Except now we will be adding the 30 gallon water storage tank at the Harden House that has two supply lines. The two supply lines allow us to switch from them using the 30 gallon tank or having our solar thermal system from our 108.6 gallon water tank preheat their water. Therefore, during the colder season (Nov-Feb) in Austin the Harden residents will draw hot water from their own tank and during the hotter seasons (Mar-Sept) the Harden residence will draw their hot water from our tank. I think the hybrid system is best explained in the diagram below.

Of course, this poses a new question for us all....During the hotter seasons will this work? Since the Harden residents did not move in until January, at the moment we do not have a answer to this question. Another questions to consider is; will we still be wasting a large amount of water using this hybrid system during the warmer months? And, just how much will the flash heater be contributing and driving up electrical usage?

I guess we will just have to wait and see what the data has to report. Nevertheless, the Harden house will have easier access to hot water than before.

Peace-

Sharing Hot Water- Does it work?

2009-01-26T18:31:00.015-06:00

The Solar Harden Duplex is unique in many ways, one of them being a system set up to share hot water between the two buildings. Now that we have tenants in the Harden House, we are able to really analyze how this system is or is not working.
The SNAP House Solar Hot Water System: When the UT students designed the SNAP house one of the features they integrated was a solar thermal system. Solar thermal systems in basic terms takes the energy from the sun and uses that energy to heat water. This of course offsets cost associated with energy used to heat water which is attributed to 14 to 20 percent of the total electricity used in a home. Our hot water system has four main components: 16 Sunda's Seido evacuated tubes-solar collectors (image above), a 108.6 gallon hot water tank Stiebel Eltron SBB 400+ Twin Coil tank (image to the left), Seisco tankless water heater model RA-9 "flash heater" (image below), and a mixing valve.

The process for the system is as follows: solar collectors act as a low-resistance thermal conductor and heats a polypropylene glycol mix (similar to anti-freeze) that is slowly circulating through copper tubing in a closed loop system. This coil acts as a heat exchanger and is coiled back in forth inside the tank in order to heat the water. In case the water in the tank is not hot enough, an electric flash heater increases the temperature. If the water in the tank is too hot, the mixing valve works to maintain a decent temperature so that we do not burn ourselves (technical details are available from the websites listed below).

The hot water arrangement between the two homes
One of the experiments Blackland really wanted to try out is sharing hot water between the two homes by having only one large storage tank for both household demands. Therefore, the Harden house does not have a hot water tank but instead pulls all of its needs from our system. Hot water travels approximately 55 feet from the tank to the Harden shower head and 62 feet from the tank to the kitchen where a Harden resident is demanding hot water.

For billing and usage purposes, we record how much water they are drawing from our system everyday by reading a sub-meter on the unit (image above).

How is it working?
According to H2ouse.org (http://www.h2ouse.org/index.cfm), the national average for the daily per capita use for a shower is 11.6 gallons and for faucet usage (bath/kitchen) it is 10.9 gallons.

When assessing the recorded hot water usage at the Harden household (1 adult and two kids) their average usage per day has been 112 gallons.

Now, if we assumed that each family member took a shower and utilized hot water for each faucet for a day; then based on the measurements supplied by H2ouse.org, their daily usage would be around 60 gallons per day. However, what is being recorded is twice as much water.

Of course, there can be many reasons why their hot water demand is so large. One variable in particular is how far the water needs to travel to the point of use. When composing some intial test at the Harden House before the residents moved in; it would take approximately 3 minutes until temperature change occured through the Harden bathroom faucet. In addition, the Harden residents estimate that they wait a couple of minutes each time for the shower to get hot.

Thus, this arrangement is causing three problems that need immediate attention:

First, the distance that the hot water is traveling is wasting an enormous amount of water.

Second, during the winter time when the water is not being heated enough by the thermal tube collectors the flash heater is kicking in to heat the water. This is causing the SNAP house electric bills to be higher than ever before.

For example, for a day where the Harden household used 180 gallons of water and the SNAP household only 50 gallons (we purposefully did not take showers, do laundry, use the dishwasher, or use our mini-split HVAC system) our electric meter recorded 17 kWh. On a similar usage day before the Harden residents moved in our electrical usage recorded was 8 kWh. So, we can theoretically assume that the flash heater is driving our electric usage to be much higher.

Finally, in a series of days where it is overcast, there is limited hot water. Thus, water is not being heated by the solar thermal system and the tankless water heater is doing all the work. If the Harden house is using the hot water at the same time, there is only a limited amount of draw from the system and it (the flash heater) cannot handle the demand.

In other words, our shower faucet maximum flow rate is 2.5 gallons per minute. At 2.5 gallons per minute the tankless water heater can raise the water temperature 24 degrees Fahrenheit. However, if we are taking a shower and the Hardens residents are also taking a shower the ability of flash heater to increase the temperature of the water decreases almost by half.

Our suggestions:

We are meeting with Blackland on Thursday afternoon and we are going to recommend that they consider installing a separate hot water system at the Harden house. We will keep you all posted on the outcome.

Product Information
Solar Thermal Storage Tank
http://www.stiebel-eltron-usa.com/pdf/brochure_sbb.pdf
Sunda's Seido evacuated tubes-solar collectors
http://www.sundasolar.com/product_index.html
Seisco tankless water heater model RA-9
http://www.seisco.com/orderpage.html

HVAC, Rainbarrels, Gardens, and Neighbors

2009-01-10T14:09:00.008-06:00

It has been an active past couple of weeks here at the SNAP-Harden Duplex. This was the view from our home a couple of night ago!

First- the HVAC mini-split system is operable and working very well. The temperature takes awhile to stabilize itself in the space, so we need to anticipate when to turn on the heat in order to maintain warmth throughout the evening. We do this by simply paying attention to the weather and asking ourselves questions such as: is it going to be cold for an extended period of time, or is it going to be cloudy (remember our passive system works well too) for a long time? To learn more about our HVAC system, read the previous post.

The next project involving the HVAC system is to design and build screens that hide the air handler, but allows more airflow. Currently, there are wooden panels with 1/2 inch slates blocking the airflow. I will upload pictures of these soon.

Secondly, even with minor rainfall this past week, our rain barrels filled up and are running smoothly. There are two water tanks on the site. One is at the Harden House and the other is located at the SNAP house. Both are on the west facades of the building. They are Norwesco Freestanding Water Tanks (http://www.norwesco.com/page.cfm?menu=36) that have a capacity of 400 gallons each. This is plenty of water for the three garden beds that we are maintaining, and since we have been living here, I have only used the city water for 7 days.

Speaking of garden beds, I spent a good amount of time clearing and pruning the garden bed last weekend, and discovered some intruders- which could be either Cankerworms or a Cabbage loopers http://www.ces.ncsu.edu/depts/ent/notes/Vegetables/veg04 0 e/veg040e.htm. My friend, Christi Greene, is a Master Gardener and she suggested spraying everything with BT (Bacillus thuringiensis). I took her advice and will probably need to spray again next week. They sure like our bok choy and spinach. However, even with those varmints in the garden everything is going well. The radishes are going strong and the broccoli is as well.

The final news we have is we now have neighbors at the Harden House. We haven't met them yet, but I have recorded their energy and water consumption data. This is very exciting data because now we can begin to see how these two homes are working together. For those of you who don't know, the SNAP house will be sharing it's electrical generation and solar thermal heated water with the 1930s house at the front of the lot.

Once the solar is generating power, we will really be able to see how a house like ours can help to keep utility bills affordable for two low-income families in the Blackland Neighborhood.

A Week Away

2008-12-31T09:03:00.002-06:00

Adam and I traveled to New Orleans for the holiday season. Therefore, there is not much to report about the home. However, when we returned, the HVAC was still inoperable. Thankfully, Austin, Texas has warmed up a bit, so the passive design of the building and the envelop (SIP panels) is enough to keep the home temperature at a range of 65-69 degrees. For us, this is a perfect temperature.

The type of system that the house integrates is called a mini-split system, Mitsubishi Electric Mr. Slim http://www.mrslim.com/.
This system consist of a compressor outside and two air handlers/vents. In basic terms, this system by passes the need for duct work, thus reducing the associated cost with leakage and poor instillation. The controls are very user friendly and when the system is working, it effectively heats/cools the house and can be as efficient as a 18 SEER system.

The 2005 SNAP House

2008-12-20T11:54:00.004-06:00

The SNAP House was designed and built by students at the University of Texas at Austin. Go to the following website to learn more about the features of the home and the project which competed in the Department of Energy Solar Decathlon Competition.

http://www.ar.utexas.edu/utsolard/2005/livehere.html

Some Historical Pictures of the Solar and Harden Duplex

2008-12-20T11:45:00.005-06:00

Attached are several pictures of the amazing volunteers who made this project possible. If you have been involved in this project in some way and would like to post a story about your experience, please contact us at slperrone1@yahoo.com

Best

A Chilly Week

2008-12-20T11:35:00.003-06:00

Boy, are we grateful that this house is made out of Structural Insulated Panels (SIPs) which consist of solid polystyrene foam 6" core sandwiched between two gavalume sheathing. This type of wall/roof system has a high R-value (measurement of thermal-resistance ) of R-27.6. With the weather being below freezing for three nights straight this week and our heat being out of commission, we were able to sustain ourselves (with a space heater) inside with the lowest indoor temperature recorded at 48.4 degrees. The space heater, of course, drove our energy usage through the roof record daily usage of 33 kWh.

The gardens also managed to survive the freeze and the seeds in the garden closest to the Harden House are finally growing. Hopefully, by end of winter we will be able to harvest some carrots, beets, and radishes.

We will be heading out of town for the holidays, so the activities around the home will be quite. We hope that the new year will bring us a working solar system and a way to record the information.

Happy Holidays,

Stephanie and Adam

A Social History-By Bo McCarver

2008-12-07T11:53:00.003-06:00

The residential architecture in the Blackland neighborhood has evolved over the passed hundred years to be highly varied in design and use. Before the area was subdivided in 1908, it was farmland cultivated by Swedes; some built homes on the Glissmann Addition lots and remained in the area. In 1928, the city adopted a master plan that called for displacing the African American population from neighborhoods west of the Capitol to an area east of East Avenue (now roughly IH-35); south of Manor Road, and north of the Colorado River. By 1945, many of the lots in the Blackland Neighborhood were purchased by black families who constructed modest bungalows, generally with two bedrooms.
The Harden House, named for the family that built it in 1945 and lived there until 2004, was typical in size, use and history. Constructed during an austere economy near the end of WW2, the two-bedroom house had no studs in its load-bearing walls but had milled 1" X 10" boards that were "tied" in the centers to each other with strips of tin tacked on so as to prevent the boards from warping and sagging. The 2" X 4" rafters were secured with "cut nails"- square, 2 1/2 inch nails made of mild steel, the crowns of which easily flattened when hammered.

As the Harden family grew, the front porch was converted to a living room and an additional bedroom was added and the roof extended over it. A different size of hardwood was used for the floor.

Minnie Harden lived in the house until her death in 2002. Her daughter, June Harden Brewer, then sold the house to the University of Texas. Meanwhile, the Blackland Community Development Corporation (BCDC) had embarked on a program of acquiring older homes and moving them onto vacant lots to be remodeled for low-income housing. Recognizing the historic and fiscal qualities of the Harden House, BCDC board members approached the UT Campus Land Development Office who agreed to donate the house to the non-profit. Because providing low-income housing was not in UT's scope and mission, it first sold the house for $10 to the Texas Affordable Housing Corporation (TAFC), a non-profit, that in turn sold the house to BCDC for legal fees amounting to $2,000.

The transaction was delayed, however, because the UT School of Architecture needed the Harden House as a storage and service facility as it erected its entry for the 2005 Solar Decathlon. The 2005 Solar D team wanted the house to be used after the competition in Washington D.C. and solicited proposals to several non-profits. BCDC was awarded the house, with the understanding that surplus energy would be shared with other rental units nearby. The solar house was added to the transfers from UT to TAFC, to BCDC in October 2005.

Working with volunteer professional engineers, architects and the '05 Solar D team, BCDC quickly garnered permits and put down pier foundations for both houses. The solar house piers were placed on limestone approximately 5 feet below ground level while the Harden House was placed on concrete footings. When the modular sections of the solar house were placed in November, a bearing under the last section was dislodged and resulted in a 3/16 in gap (discovered a year later). Meanwhile, the Harden House survived the four-block move northward after a section of the roof was removed to allow it to pass under a power line. The sparse use of materials in the Harden House was not discovered until after it was moved and demolition exposed the 1 X 10s that composed its load-bearing walls.

The housed were placed on two lots that had been platted from one lot in 1940. It was soon discovered that Texas Deregulation Laws do not allow energy to be transported across lot lines, an unanticipated situation that jeopardized the major objective of the project. Joel Martinez, BCDC's architect, suggested joining the two lots together in a restrictive covenant and building a breezeway across the 15' space that separated the structure, thus producing a duplex. The plan triggered another round of variance requests but these were secured in early 2006 and work proceeded.

The exposed roof of the Harden House needed immediate attention so volunteers first addressed that issues and then performed demolition on the moldy Sheetrock and other internal structures. Donations were received from Shelter with Spirit and Grande Communications that kept the volunteers supplied with materials. BCDC dedicated $790 per month from its meager development budget that came from rents paid by 37 households living in the non-profit's units.

Hundreds of volunteers worked for several years on both structures. The dedication of the duplex was held in August 2008 and also marked the BCDC's 25th anniversary.

The Harden-Solar Duplex project generated much information that informs BCDC's next effort, the Stewart Site, where green building techniques will be deployed in renovation and construction of eight residential units for low-income household and community conservatory where domestic arts and community culture can be fostered.

Links to Local Press Articles

2008-11-16T08:05:00.002-06:00

Here are two links to articles composed about the unique social and technological experiment being composed at the Solar and Harden Duplex.

Austin American Statesman: http://www.statesman.com/business/content/business/stories/statesmanhomes/10/05/1005weird.html

Austin Chronicle: http://www.austinchronicle.com/gyrobase/Issue/story?oid=oid%3A671779

A Welcoming Post

2008-11-16T07:57:00.005-06:00

Welcome to the Solar and Harden blog. This blog will be maintained weekly by Stephanie Perrone-Freeborg to inform others about this unique solar living experiment. Please check out the "Social History" post to read a historical background about this building. Also, check out the links to article composed by the Austin American Statesman and The Austin Chronicle. These are both a good start for orienting yourself to our home.

Check back weekly to learn about the work that is being done, the amount of energy that is being generated by our 7.9 kWh system, and any other general observations.