Tag Archives: efficiency

Adding Insulation for Energy Efficiency Part 1

adding insulation for energy efficiency

Untitled” by Jesus Rodriguez // CC BY

As we continue to explore the possibility of building a house that doesn’t require a heating and cooling system, the next step is to get to know the current standard for adding insulation for energy efficiency. This is a topic that involves a bit of math. In this post, I’ll walk you through the equations that are used to determine how much insulation to add. In the next post on insulation I’ll go through two simple examples of working out how much insulation to add.

Payback Period

The typical plan for adding insulation for energy efficiency is to add to the point where you are able to cover the costs of the added material with the money that you will be saving in heating and cooling costs. The time it takes to recoup the money for energy efficiency upgrades is called the payback period. For the insulation of a residential building the average payback period that most people are interested in waiting is between 4 and 5 years. So, in order to figure out the payback period we need to consider the R-value of the insulation, and the cost of heating and cooling the house per year.

Calculating the R-Value

As you may remember from my last post on insulation, the R-Value is a numerical value given to insulation that tells you how much the insulation is going to resist the flow of heat. Determining the R-Value of an insulation material depends on a number of different factors:

  • Initial indoor temperature (Ti)
  • Outdoor temperature (To)
  • time (t)
  • surface area of the building (A)
  • The heat loss indoors (dQ)

And the equation looks like this:

R = (Ti – To) * A *t / dQ

The good news about R-Value calculations is that you usually don’t have to do them. Since the measurements to complete the calculation are done in a lab setting in a controlled environment, the insulation manufacturer provides that information for you when you choose your material.

Calculating the Payback Period

In order to calculate the payback period of adding insulation, we need to take into account the insulation and the heat system.  The payback period depends on the following features:

  • R-value of the initial insulation (Ri)
  • R-value of the final insulation (Rf)
  • Cost of insulation (Ci)
  • Efficiency of the heat system (E)
  • Cost of energy (Ce)
  • Number of days that require heat per year (t)

And the equation looks like this:

P = (Ci * Ri * Rf * E) / (Ce * (R2 – R1) * t)

You can find more information on calculating the payback period of adding insulation here.

I know looking at all these equations can be intimidating if you are interested in figuring out how much insulation to add to your house to meet the 4 – 5 year payback period. But hopefully after I work through a couple examples in my next post on insulation, it will seem manageable. Maybe you’ll even be inspired to add insulation to your own house to make it more energy efficient.

Hang Drying Laundry in the Winter

Clothes dryers are an incredibly inefficient use of electricity. The typical dryer uses in the neighborhood of 5 kWhs of electricity, even energy efficient dryers use at best around 2 kWhs during their dry cycle. (To put that in some perspective, that’s the same amount of energy as a 100 watt incandescent bulb uses in 20 hours – or in the case of my 9 watt LED light bulbs, 220 hours!) In fact, running a clothes dryer uses more energy than any other appliance in a typical American household. That’s a lot of energy just to spin some hot air around.

These days, what with cloth diapering Cheeks McGee, I’m doing a load of laundry about every other day – 4 loads a week, we’ll say. And living in an apartment, we pay $1.50 for each cycle. Which means that if we were drying all of those loads, it would tack an additional $24 onto our expenses each month. That’s $312 a year.

So in the interest of saving energy and money, we hang dry our clothes. As I’ve written about before, in the summer heat and sun, our laundry is dry within a few hours. Now that the winter has firmly decided it’s here, we continue to hang dry our laundry, but now we hang it indoors. The shared basement laundry room in our apartment complex already had clothes lines, but in the past we’ve used a folding drying rack, the backs of chairs, the shower curtain rod, and basically anywhere else we could possibly hang a piece of clothing. It does take more than 3 hours for our laundry to be dry, but never longer than 24 hours. I bet aside from sweatshirts, most of it would be dry by morning if they hung over night. And running your clothing through the spin cycle can be really hard on it, so by hang drying we get more life out of our clothing as well.

Yes, we have to think ahead more than 2 hours if we want to wear something that is currently dirty. But right now, with the frequency we are doing laundry, that hasn’t been an issue. And in a clothing emergency, the dryer is still right there.

Amory B. Lovins on Integrative Design

I’m going to give you a little bit of homework before we get into the meat of this post. Watch this video:

(I’ve probably posted that before. I’m a wee bit obsessed with Mr. Lovins and his work)

Now let’s talk a little bit about integrative design. Integrative Design is a method of design based on working from the top down. Basically you look at the entire system – the entire car, the entire house, the entire factory, with the intention to make it as energy efficient as possible. By looking at design from the top down you ask how to make the best holistic design by intertwining the functions of the different components.

Integrative Design is different from traditional design methods which focus on optimizing each individual piece of the system and then fitting them together and adjusting how they interact. This traditional method creates the most optimized walls and plumbing and HVAC. But the integrative design approach allows you to say, what if we didn’t need the HVAC at all  (or at least not our idea of the most optimized HVAC) because we change the way we build the walls completely.

At the end of the Autodesk video Amory mentions the 10xE principles of integrative design, and I want to share those here:

  1. Define shared and aggressive goals.
  2. Collaborate across disciplines.
  3. Design non-linearly.
  4. Reward desired outcomes
  5. Define the end-use.
  6. Seek systemic causes and ultimate purposes.
  7. Optimize over time and space.
  8. Establish baseline parametric values.
  9. Establish the minimum energy or resource theoretically required, then identify and minimize constraints to achieving that minimum in practice.
  10. Start with a clean sheet.
  11. Use measured data and explicit analysis, not assumptions and rules.
  12. Start downstream.
  13. Seek radical simplicity.
  14. Tunnel through the cost barrier.
  15. Wring multiple benefits from single expenditures.
  16. Meet minimized peak demand; optimize over integrated demand
  17. Include feedback in the design.

In Amory’s lecture he talks about using integrative desing in building design for heating and cooling, in auto design for using less fuel, and in factory design for pumping fluid. Stay tuned for a bit of a deeper dive into these topics in the future, including how the integrative design principles lead to radically different approaches in each of these categories.

Tell Me More About Energy Star

Chances are you’re familiar with the blue and white logo that can be found on many types of home appliances, but do you know what being Energy Star certified actually means?

The Energy Star program was started by the Environmental Protection Agency and the Department of Energy in 1992 as a labeling program for energy efficient appliances. Energy Star is now an international standard for energy efficiency. The Energy Star label can now be applied to computers, servers, appliances, heating and cooling systems, home electronics, imaging equipment, lighting, and new homes and buildings.

In 2010 it came to light that the Energy Star label was being wrongly granted and misused. It was being granted to products that did not exist, and if a company had one product certified they were able to download the label and put it their other, non-certified products as well. Since then, a number of critical audits were completed, and the Energy Star label and certification process has been revamped to prevent these sorts of fraudulent claims.

Now each application is reviewed for approval. Products must be third-party tested in EPA approved labs. Additionally, each year off-the-shelf tests are conducted on a percentage of Energy Star labeled products to ensure that the consumer is receiving products that meet the standards.

So what does it mean if something has and Energy Star label

Each product has a set of standards that it has to meet in order to receive the label. For example, a refrigerator must save 20% of energy based on the industry minimum standard, an air conditioner must save 10%, and a light bulb must save 75% vs a standard incandescent. These standards are updated every couple years or so, in particular when at least 50% of the market is held by energy star labeled products.

The Energy Star label and buildings

There are currently Energy Star ratings for new homes, commercial spaces, and industrial plants. Buildings are evaluated for the energy efficiency of their heating and cooling systems, water management, and air quality. Buildings are evaluated by professional engineers or registered architects and have to receive a rating of 75 or higher (out of 100) in order to receive an Energy Star label.

LED Light Bulbs

I hope you all had a lovely long weekend. Between the Holiday and adjusting to the ever changing schedule that is medical residency, Tuesday’s post got away from me. I hope you didn’t miss my wrap up on light bulbs too much. 

LED Light BulbLED stands for Light Emitting Diode. LEDs are comprised of a semiconductor material and two leads. Basically what happens is that when the LED is connected to a circuit, a voltage is applied to the leads. This provides enough energy for electrons to jump across the band gap, and when they do, they release energy in the form of photons, or light. The color of light emitted by the LED is determined by the band gap in the semiconductor. If all this talk of semiconductors sounds vaguely familiar, it’s because it’s the same concept behind solar cells. Only in this case, the energy is coming from the wall rather than from the sun. LEDs are great as far as energy efficiency goes because they require a very small amount of electricity to produce light. They are also compact, robust, and have long lifetimes. LED light bulbs are made up of a collection of LEDs designed such that they emit a white, or slightly yellow light. Recently LED light bulbs have become increasingly available for home lighting, so let’s see how they compare to Incandescent and CFL light bulbs.

  • Light Quality: Mixed Reviews. Like CFLs I have frequently read reviews that LED light bulbs produce light that is too cold. We can probably all easily identify LED holiday lights because they have that tell-tale blue tinge to the light. I am happy to report that the LED light bulbs that I recently purchased produce a warm soft light, just like we expect are accustomed to seeing from incandescents. LED light bulbs will probably need to become more mainstream before they beat the cold blue light rap.
  • Price per bulb: Con. Standard LED light bulbs typically run $10 a bulb. If you buy them in a six-pack you can get them for more like $9, but there is definitely a bit of sticker shock that comes with spending over $50 on lightbulbs just for your home use. And if you want anything fancy, like a dim-able bulb, you’ll easily be paying double.
  • Availability: Pro. You may not be able to find LED light bulbs on the shelves of your local grocery store yet, but Target, Home Depot, and Amazon all carry them, and I imagine many other stores as well.
  • Style: Con. Similar to CFLs, LED light bulbs fit standard sockets, but the choice of bulb is limited. There are candelabra bulbs, but they don’t look the same as the incandescent equivalent.
  • Energy use: Pro. An LEDbulb that produces a comparable amount of lumens as a 60 watt filament bulb requires only 9 watts.
  • Lifetime: Pro. 25,000 hours! You read that right, a LED bulb will last more than 3 times as long as a CFL bulb. That translates into nearly 23 years of light at 3 hours a day. The LED light bulb that I recently put in our lamp will burn for longer than my youngest brother has been alive. That’s crazy town.

And bonus: LED light bulbs contain mostly recycle-able materials. Contact your local recycling provider to see if they can recycle your old bulbs. Although, you can probably wait 20 years  or so before you have to deal with that.

So the tally when comparing LEDs to CFLs and Incandescents is 3 pros, 2 cons, and 1 mixed review. Now let’s look at the long term cost.

10 year cost for burning filament bulbs in one lamp: (3 hours a day, $0.12/kwh cost of electricity, $9.00/bulb, 1 bulb) = $20.83.

And bonus: that same bulb will burn for another 13 years at that rate.

Pretty cheap when compared to the $96.84 it would cost to run the same light with a incandescent bulb, and it even beats out the $22.40 for the CFL. 

And more importantly, over that same 10 years you could save 550 kWh of electricity if you switch from an incandescent light bulb, or 55 kWh if you switch from a CFL.