Solar Retrofit

My Solar Retrofit – An Energy Audit and a HERS Score

by nan on 2011/02/28 · 1 comment

(This is Part 7, the final installment of a series about the solar remodel I did on my house in 2007. Start here.)

The interior of the remodel was not complete, but the envelope was done enough to conduct an energy audit. I called my friend, Alva Morrison, who is a Certified Energy Rater. He’s been working in the state weatherization program for a long time and is very knowledgeable about energy conservation. Becoming an energy rater was a natural next step for him in his career.

We were going to conduct a blower door test. A huge fan was placed in the opening of an exterior door and sealed to be air tight. Then we sealed up the other exterior doors, closed all the windows and left all the interior doors open. We were going to need the air in the house to flow to the fan and outside in order to determine leaks.

Here are pictures of the fan from inside the kitchen and outside.

Alva measured the house to determine to volume of air it holds. He also asked me a lot of questions about my heating systems, insulation, building materials and the foundation. I also gathered up my utility bills so he could see my average annual energy use. All that data was input into the software on Alva’s laptop.

We put the laptop on a table by the door, and connected the fan to the laptop. You can see all the cords in the photo on the left. We turned on the fan, and it recorded the air flow through the house. At the same time, it analyzed the results based on the other information I had given him.

While it was running, we went around the house looking for air leaks. We were surprised to find them in some places and not in places where I expected them! The older windows had some spaces around them, and we caulked them. There was also a small space in the panel where I gain access to the attic space. We tightened that up, too, then rechecked the figures the software was spitting out. With just sealing up those areas, we had improved the house’s energy efficiency.

We were surprised at the analysis, recommendations and ROI, too. Alva included them in his report:

“Nan’s house is a great example of what can be done to turn a pretty average house, built to code a couple of decades ago, into a modern energy-efficient home. If built as is today, it would exceed qualification for the USEPA Energy Star certification, even though many of the walls still have 2×4 insulation in a 2×6 wall. The main factor driving the house’s lean performance is a thick blanket of attic insulation. But the solar hot water and the balmy sunroom, with a thick adobe wall to catch and hold the heat, provide solid backing. Add to that a refrigerator, which squeezes kilowatts until they scream, and you have a working person’s house to take us all through the next century of global warming both economically and comfortably. All these things were added to the house by Nan at moderate expense.

“Analyzing possible improvements was very interesting. Tearing off sheetrock and re-insulating the walls seemed like it should be a no-brainer. But when we ran it through the computer, it only showed a savings of around $25 a year- not much reward for all that trouble. The moral is, heat goes up, not sideways.

“However, we found another weaker spot in the building’s ‘heating envelope’: the uninsulated foundation. A quick rework of the house through the energy rating software showed that digging a barrier of four inch rigid foam in around the perimeter of the foundation would return $175 a year – and that’s if the cost of wood and gas stays the same (don’t hold your breath for that!). Get out your shovel, Nan!”

Hopefully, I can get that work done this summer. It’s kind of back-breaking for me, but I have some energetic friends that could pull it off.

I had Alva calculate a HERS (Home Energy Rating System) score, because I wanted to be able to show others the entire process. Tangible results say so much more than academics.

The number of a HERS score is based on the International Energy Conservation Code (IECC), which is 100. My score was 88, meaning my house is 12% more efficient than the code. The lower your number, the more efficient your home is. When I make improvements, Alva can plug that information into his software, analyze the results again, and give me new recommendations.

Many municipalities, including Taos, are beginning to require HERS scores and/or LEED certification on new construction. This is the only way were are going to get our building to be more efficient. I have found over they years that voluntary energy conservation doesn’t work. Mandates do.

I have now lived in the house for four winters since the remodel. My energy bills are very low. Here are some thoughts on energy:

> My gas bill for hot water, cooking and heating my daughter’s rooms rarely goes over $30, and in summer, it’s usually $18.

> Instead of burning 5-7 cords of wood, I burn about three. This is always hard to judge, because there’s usually wood leftover from the year before, and I burn a lot of scrap lumber and paper trash when it’s not very cold in spring and fall.

> I did not install solar PV, because my electric bill is about $25 a month. It would not be cost effective to install, since the payback would take so long. If I were gung ho about generating my own power and returning it to the grid, I would definitely have PV on my house. It would be a wonderful experiment!

> When I think of selling and moving closer to town for walkability and a smaller home, I figure my bills will be much more than they are here. Even though I have more space than I need, and I have to drive everywhere (I don’t drive to town every day, though), I am still using less energy than I would in a smaller home closer to conveniences. The gas bill in my hybrid car is certainly less than an increase in rent and utilities, so from a financial point of view, I am probably better off staying put until I sell and move away. There are always trade offs in the energy conservation game.

> I’ve cut my grocery bill by being able to grow food indoors year round. It doesn’t take much to do this. A few pots with greens and other cool weather vegetables offsets my food bill.

> Low-e windows and insulation work wonders to reduce energy consumption! I also bought a front-loading washing machine just before this remodel, and it measurably cut back on my hot water.

> Find a certified local Energy Rater through RESNET – Residential Services Energy Network.

Thanks for reading about my remodel! If you have any questions, please don’t hesitate to email me! nan at desertverde dot com.

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My Solar Retrofit – Solar Hot Water

by nan on 2011/02/22 · 3 comments

(This is Part 6 of a series about the solar remodel I did on my house in 2007. Start here.)

One thing I had wanted in a home for many years was solar hot water. I’ve had solar showers for camping (and power outage emergencies!), so I was aware of the power of the sun to heat water.

I understood how it worked, but I did a lot of research anyway. I found this at www.energysavers.gov:

Solar water heaters—also called solar domestic hot water systems—can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use—sunshine—is free.

Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don’t.

Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.

Two tank solar hot water system:

One tank solar hot water system:

My next step was to call installers for quotes. I first called (and ultimately hired) Valverde Energy. Larry Mapes, the owner, came out to the house, and we talked about my energy needs. My daughters were in high school and close to going to college. We decided to size the system for my future use living here alone. It could be added onto later when a family lived here again. The system would have been too large if I’d put in enough panels to cover laundry and hot shower needs for me and two teenage girls.

We installed a two-tank, active system, like the top image. The cost was about $7000. We crunched numbers and saw that it would pay for itself with energy savings in about six or seven years. I am halfway there! Actually, with tax credits, I’m probably even closer. I haven’t calculated that figure, but nevertheless, I love that the sun heats my water and that in a couple more years, my hot water will be free!

My solar panel being installed on the roof:

To make the most of solar hot water, it needs to be used in the middle of the day while the sun is doing its work. Later in the day, it is still effective, but not so much. I’ve already written about how to maximize your solar hot water.

My girls were home for two years before heading off to college and boarding school. Once I was home alone, my gas bill for hot water was about $15/month. I don’t make elaborate meals for myself, so that cost was mostly for hot water needs. When the girls are home on vacations, the gas bill does not go up much, since they sleep late and shower in the middle of the day or in the evening. I now have one living at home, and even with heating that room, my gas bill is not above $30. I credit this to the solar hot water AND a front loading washing machine.

Move on to Part 7, the final installment!

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My Solar Retrofit – Thermal Mass

by nan on 2011/02/14 · 2 comments

(This is Part 5 of a series about the solar remodel I did on my house in 2007. Start here.)

The way passive solar works is that the sun hits a mass, which absorbs the heat. As temperatures drop, the heat is radiated out from the mass. It’s a constant cycle of absorb and release based on the thermodynamic law that heat moves to where it is cooler. Again, I’ll bring up the hot summer sidewalk example. When it’s hot, it is absorbing the sun’s rays and heat. At night, it sends that heat out. This is why cities don’t cool off at night. Their concrete and asphalt are radiating daytime heat into the cool night air.

I have several sources of thermal mass in my greenhouse. An adobe wall was built along the north wall. The sun hits it, it absorbs the heat, then sends it out at night to heat the space.

This is the wall as the contractor was in the process of cleaning the mortar off of it:

This is my garden on January 1, being heated by the thermal mass:

This is a close-up of the tomato plants along the adobe wall on January 1:

The concrete wall of the planter bed also gets a lot of sun. I walk along the top of it to close the the curtains at night, and it is toasty! The soil in the bed and the concrete floor serve the same purpose. There are many areas where the sun comes in during the day, and each has the ability to absorb its heat.

The beauty of this radiant heat is that there are no cold spots in the room. It’s comfortable everywhere. It’s a very gentle heat.

Water is another excellent thermal collector. I’m sure you’ve seen pictures of solar greenhouses from the 70s where 55-gallon drums were painted black and filled with water as thermal mass. Sometimes you’d see the north wall of a greenhouse lined with 1-gallon jugs painted black. It’s all the same – mass to collect the sun’s energy to heat the space at night.

It’s great to have sunny windows to heat your home during the day, but they are even more effective when you can store the heat with some type of thermal mass for nighttime use.

Move on to Part 6!

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My Solar Retrofit – Energy Efficient Windows

by nan on 2011/02/01 · 2 comments

(This is Part 4 of a series about the solar remodel I did on my house in 2007. Start here.)

Even though the greenhouse was not in full swing by the following spring, it had served its purpose over the winter of pre-heating the air for the other parts of the home. It is much cheaper to heat warm air than cold, as you can imagine. My heating costs were cut dramatically!

But not just because of the greenhouse.

I replaced about 2/3 of my old single pane and outdated double pane windows with vinyl low-e windows from Lowe’s. The reason I mention Lowe’s is to let you know that a remodel does not have to be outrageously expensive. Most of my materials came from Lowe’s and Ace Hardware, 1) because they were local and inexpensive, and 2) I chose to put my money into the infrastructure and solar panel.

Back to windows…..

I have written in-depth about energy efficient windows, so I am not going to repeat the details about what to look for on a label. If you know what to look for, though, you can buy good windows at Lowe’s or a high-end window dealer.

My house is an old ranch that is about 40-50 years old. A LOT of the windows were single pane. Even my sliding glass door was single pane! I replaced them all with these great windows from Lowe’s.

I am not exaggerating when I say my heating bill was cut in half. The construction was mostly done by Thanksgiving, and I was excited to be going into winter with this ‘new’ home made for energy efficiency.

With new windows installed, I could immediately feel the difference in how the house got warmed and how it retained the heat. It was amazing. I was too hot. I had to relearn how to build a fire. Instead of raging, it could be gentle. I had bought my typical five cords of wood that fall, and I knew right away it would be too much. Sure enough, that wood lasted me two years.

Efficient new windows and a greenhouse are not the only reasons it was so easy to heat my house. You know how heat rises? Well, if your ceiling is not insulated, your heat will move right out the roof. That’s exactly what mine was doing. Until now.

I have written about ceiling insulation before. I guessed I had about R19 of shredded fiberglass up there, so I blew in R30, for a total of R49. What a difference! The house is cooler in summer, too.

You don’t have to build a solar greenhouse to save on your heating bills. Add insulation to your ceiling and replace old windows!

Move on to Part 5!

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My Solar Retrofit – The Solar Greenhouse Gets Framed In

by nan on 2011/01/25 · 1 comment

(This is Part 3 of a series about the solar remodel I did on my house in 2007. Start here.)

It was thrilling when the walls went up and the roof went on, especially as I tracked the autumn sun into the greenhouse. I was really looking forward to winter with this addition! The solar panel for hot water is on the roof to the right. More about that later.

The cat checks out the interior space. She loved to sit on the open window sills. She was disappointed when the glass went it! Rather, she had to adjust to a smaller, but warmer, space. The open dirt area on the left will be the planting bed. The plumbing for the sink is stubbed out beside it. The skylights are framed in the roofing.

The south glass and skylights are in, and the wall creating the planting bed has been built. Two double-hung windows went in the far wall. The X on the ceiling to the right is where one of two operable Velux® skylights were installed. The greenhouse is ventilated by opening the windows and the skylights. Hot air will be whisked up and out. The adobe wall on the right will be thermal mass to retain the heat from the sun. It looks like it’s working already, huh?

Move on to Part 4!

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My Solar Retrofit – Building the Solar Greenhouse

by nan on 2011/01/18 · 0 comments

(This is Part 2 of a series about the solar remodel I did on my house in 2007. Start here.)

The room with the big picture window was once a two-car garage long before I owned the house. It was a photographer’s darkroom when I bought it, and it had undergone many changes since. Now I divided it exactly in half for two identical rooms for my daughters. Hopefully, there would be no more bickering about whose room was bigger or better! They even have matching doors that were recycled from other parts of the house. Pure equality!

The wall between the rooms is going in:

This is the ‘after’ picture:

These are the bedroom doors from the outside where the solar greenhouse will be built and serve as a hallway:

The blue door to the right is the second bathroom that will belong to the girls, so they essentially will have their own wing with a bathroom and the greenhouse. Heat from the greenhouse will move into their rooms and the bathroom.

Off to the right (below) is the door to the main living area and kitchen, and air will be able to move freely and heat those areas, too. The new floorplan is much less choppy and easier to heat and ventilate. And it used to be you had to walk through one bedroom to get to another, so that problem has been remedied as well.

The walls of the solar greenhouse are going up:

Check out that autumn sun and the effectiveness of the 2′ roof overhang! You can also see the water lines for the greenhouse, and as an aside, there is my beloved 1990 Toyota 4Runner parked up on the hill. It got to be too expensive when gas was almost $5 a gallon, so I bought a slightly used (775 miles on it) Ford Escape Hybrid. The payments and the gas for that car were less than gas and repair bills for the Toyota! But I miss that rugged car!

Move on to Part 3!

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My Solar Retrofit

by nan on 2011/01/11 · 6 comments

(This is the first installment of a multi-part series.)

When I bought my house in 1999, this remodel was immediately part of my dream. I saw the potential to grow food and heat the house at the same time. It took me eight years to pull it together, but in June 2007, I got serious.

It started with a call to Valverde Energy to see about putting in solar hot water. Larry Mapes, the owner, and I crunched some numbers after talking about my current and future hot water use. Since my teenage daughters would soon be going away to college, we decided to size the system according to my needs after they left. That meant one solar panel with the option to add on for future residents.

Larry and I also talked about a photovoltaic system (solar PV). It would not have been cost effective for me, since my electric bill was about $25 a month. At 2007 prices, I wouldn’t have been able to pay off a PV system during my entire lifetime anyway. If I was insanely passionate about generating my own electricity and sending some back to the grid, I would have installed it. I was more interested in generating hot water, since that bill had gotten high with two teenage daughters.

I decided to upgrade my infrastructure at the same time I installed solar hot water by ditching my propane tank and bringing in natural gas from the new adjacent subdivision. I also replaced my aging water supply line. I am on a shared well, and, for years, we have been talking about replacing the water lines to each house. The money has never been available to do the entire job, so I went ahead and replaced my own. I was going to replace the septic tank to have all new infrastructure, but it was deemed to be in good shape via an inspection, and I did not need a new one.

I needed a contractor to do some work in conjunction with Valverde. Lots of things needed to be shuffled around as the new plumbing went in – walls, sinks, water heaters, and so on. I asked a contractor friend if he wanted to do that. I got a few bids for the bigger construction job of building a solar greenhouse and reworking a few rooms and traffic flow inside. We started work in mid-July, and the results will be documented over the next several weeks.

This corner faces due southwest where a solar greenhouse was to be added. It is not an optimal orientation, but it was ‘adequate’ according to solar building guidelines.

This area was a concrete slab that we had to remove to run the new water line from the well. The concrete is piled up on the right side, and the new water line connection is sticking up in the corner by the door. The demolished slab is piled up on the right.