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Solar Decathlon

OSU SD Update Day 12-13

brandon's picture

Submitted by brandon

Submitted on Mon, 09/26/2011 - 12:01

An Update from our Engineering Advisor Dr. Mark Walter:

Dear Friends of the OSU Solar Decathlon Team:

As I finish this message enCORE is still in 3rd place with 185.1 points. Maryland is in first place with 186.1 points, and Purdue is right between us. As always you can see the live scores here:http://www.solardecathlon.gov/scores.html. Tomorrow will be a big day for scoring. Watch what happens when the Affordability Contest results are announced sometime after 2:30. Affordability is the result of a construction estimator's evaluation of the as-built houses. It includes all the material and labor. If a house is estimated at < $250k, that team will receive 100 points. There is a shallow, linear drop-off in points for estimates between $250k and $350k (90 points at $350k) and a steep drop from $350k to $600k. No points for anyone over $600k. enCORE was designed to meet these affordability constraints. We will see how we did tomorrow!

You should definitely check out our DC gallery (http://solardecathlon.osu.edu/content/dc-gallery). There are updated photos of touring (the kids touring has been a huge hit) and new photos of the interior and exterior. These photos a really highlight the hard work that the team has put into this project. On Day 12 (Sunday, 9/25) 2700 people toured the house. This is very gratifying (and also very tiring ... hang in there team!).

Day 12 consisted of public touring from 10:00 am - 5:00 pm. By 6:30 pm the house had to be within the proper temperature and relative humidity ranges (71-76 deg. F and <60% rh, respectively) for the Comfort Zone competition. Comfort Zone must be maintained through the night and until the start of public touring on the next day. Also at 6:30 pm we had to turn on all lights and run our tv and DVD/BlueRay player. At 7:00 we had to do a load of laundry (wash and dry) and run the dishwasher. At 7:30 we had to start boiling off (vaporizing) 5 lbs (80 oz.) of water in 2 hours. Hmm, guess what vaporizing 5 lbs of water does to the humidity level of a tight house. It helps to lower humidity with the range fan and the ERV (energy recovery ventilator), but the HVAC system does have to put in some overtime. One of the major engineering innovations in enCORE is a desiccant wheel dehumidifier that is regenerated with a solar hot air collector. This system was designed as part of an interdisciplinary capstone design class at OSU. Unfortunately we have not received enough hot air to run this system, and it also does not operate at night. The Daikin Altherma heat pump system is what is keeping enCORE #1 in Comfort Zone. This system can cool (and dehumidify) the house, heat the house, and make domestic hot water. It draws about 1.6 kW thus also keeping our energy usage way down. The last measured contest of the night involved two hot water draws (15 gallons of 110 deg. F water in 10 minutes). With the exception a forgotten light on the first day of contests, the team has been perfect in all these task-contests. Impound started at 10:30.

Day 13 required public touring from 10:00-2:00. Comfort Zone re-started at 3:00 pm. Comfort Zone was more challenging since there were 4 team members preparing for the dinner party. The extra bodies and everything associated with preparing a meal worth of any 5-star restaurant is challenging. The HVAC system had to work overtime to keep the enCORE properly conditioned, and cooking is not a low-energy activity. We have seen our oven eat-up (no pun intended) 5 kW of power. If used for 1 hour that is 5 kWh, which is equivalent to leaving a 40 watt bulb on for more than 5 days. With the weather being horrible for demonstrating the benefits of solar power production, we are running an energy deficit. We are currently at about -20 kWh. There are about 4 teams with a smaller deficit. (It seems that some teams may have served sandwiches for dinner!). We have seen our array produce 7 kW (instantaneously), so with a 1/2 a day of strong sun we can wipe out this deficit. Despite having a middle-of-the-pack array size, thanks to First Solar's thin film technology, we are doing quite well in overcast conditions and, due to contest requirements, a less than optimal array angle. Day 13 had 3 hot water draws and also full-on lights for 2 hours. We are watching our energy balance carefully. If we are not net-zero (producing as much as we use), we will not receive the 100 points for the Energy Balance contest. Points scale linearly down to zero at -50kW. Lets hope for a couple of sunny days before 7:00 pm on Friday.

Stay tuned for another update soon. As always if you wish to be removed from this list, do not hesitate to e-mail me.

regards, mark

PS: Here is a quick rundown of how points are accumulated. There are 10 contests, each worth 100 points. Five contests are measured and five are subjective. The five measured contests are Comfort Zone, Hot Water, Appliances, Home Entertainment, and Energy Balance. The five subjective contests are Architecture, Market Appeal, Engineering, Communications, and Affordability. Below is what is involved in each of the measured contests. With the exception of refrigerator and freezer, these contests run over specific portions of the day. For the monitored contests, points are awarded every 15 minutes.

Comfort Zone:
   maintain 71-76 deg. F and < 60 % relative humidity
Hot Water:
   draw 15 gallons of 110 deg. F water in 10 minutes
   refrigerator between 34 and 40 deg. F
   freezer between -20 and 5 deg. F
   wash 6 large towels
   dry 6 large towels to between 100 and 110% of the original towel weight
   run the dishwasher cycle and make it reach at least 120 deg. F
Home Entertainment
   lights must be full on
   vaporize 5 lbs of water
   dinner party (cook a meal and be judged by your solar village neighbors)
   home electronics (run an organizer-supplied movie)
   movie night (show Inception and serve snacks to your solar village neighbors )
Energy Balance
   be net-zero for full points; lose points linearly until -50 kWh