Written by Sustainable Lafayette based on an interview with Joanne Tan (tan-toudic@comcast.net)

Challenge

Joanne Tan is as enthusiastic as anyone that we’ve met about making her home more energy efficient and reducing her contribution to global warming. Besides that her 30 year old furnace was often malfunctioning and left her family in coldness for a couple of days during the winter of 2006. In early 2007 she decided she wanted to modernize her home, using the latest systems to make it highly energy efficient. She was excited about using renewable solar energy and also convinced that her old furnace and traditional hot water heater were wasting a lot of energy.

Solution Details

Joanne decided to simultaneously begin three major projects in 2007: to install solar panels, replace her old furnace, and install a tankless hot water heater. All three systems were installed in the Fall of 2007 and Joanne is just now seeing the difference in her latest PG&E bills (some details below).

Solar Panels – After evaluating different vendors and different sized solar systems, Joanne decided to use Borrego Solar and settled on a 2.5 Kilowatt system (2.1 kW CEC rated) that includes 13 190 watt panels on her roof and a Sunny Boy inverter with 95.5% efficiency (shown in the picture, under the window). She chose 13 panels because it was affordable and would eliminate the most expensive electricity that she buys (PG&E has a tiered pricing model. The more you use, the more expensive it gets). Because of that, the system is expected to reduce her annual electricity use by about 35%, but reduce her annual electrical bill by over 60%. The system was installed in October and has been running smoothly.

New Furnace – Like many homeowners in Lafayette, Joanne’s home had a 30 year old furnace and she was sure that a new one would be far more efficient. She purchased a high efficiency, 2-stage, variable speed furnace made by Carrier (Infinity 96). The furnace was installed in the attic to save space and operate more quietly, and the installers put in new ducts and pipes and moved the “air return” to the upstairs so that the furnace would start with warmer air. Also, they used a new PVC concentric vent kit through the roof, which is supposed to help efficiency.

100_9788-1Most of the time the furnace operates in the first stage or low heat for greater efficiency and comfort. On colder days, if the first stage cannot satisfy the heating demand, it switches to high heat or the second stage. Joanne’s old furnace only offered one level of heat – high. “I can’t even hear it,” Joanne said. “The old one was so loud.” The furnace was also setup to heat two separate zones using the Infinity Zone Control System. Zone One is for the downstairs’ living room, kitchen, and other rooms. Zone Two is for the upstairs bedrooms and bathroom. Both zones can be controlled by a digital Infinity Smart Sensor pad (shown in picture), located downstairs, that includes vacation set up, fan-only set up, and AC cooling control. A second pad upstairs allows full control of Zone Two without going downstairs. Joanne said “It’s very smart, very friendly, and I’m completely happy with it!” Joanne raved about how easy it is to program and also to use it’s vacation function to quickly set a constant low temperature when she’s going on a trip.

100_9795-1Tankless Hot Water Heater (Gas) – Another substantial project was to replace her old hot water heater with a new outdoor tankless water heater made by Noritz (N-0931M-OD). Tankless water heaters are more efficient than standard water heaters because they heat water on demand and not 24 hrs/day. The new Noritz unit can supply 252 gallons per hour. Joanne laughed “That should be enough!” The one issue she’s found is that it can take 30 seconds or so for the hot water to start coming out of the faucet and she’s concerned that that is resulting in some wasted water.

Joanne has done a variety of other things around the house as well to save energy including replacing some windows and doors with new double-pane models.

Benefits & Payback

Electricity Savings – Borrego Solar estimated that Joanne’s new solar system would reduce her electrical use by about 3400 kWh per year and save her $1,081 per year based on current energy costs. Borrego’s estimates show a 10-15% reduction in electricity used in the winter and a 65% reduction in the middle of the summer. Her latest PG&E bill (12/12/07 – 1/9/08) showed a reduction in electrical use of 19% compared to the previous year and cut her electrical bill in half.

Gas Savings – The new furnace and hot water heater are also making a big difference. Joanne’s gas usage for mid November through mid January was 17% less than during the same period a year ago.

Informational Links

Vendors:
Borrego Solar

Products:
Noritz Tankless Hot Water Heaters
Carrier Furnaces

Leave a Reply