energy effectiveness

energy effectiveness

Exercise   1

Calculating Energy Priorities

    Time Estimate: 1–3 hours

 

   Goal: Identify opportunities for reducing lifetime energy use

 

If your product uses energy during its life, when does it use energy, and what specific components use most of the energy? Or if your product’s energy impacts are indirect (like clothes being washed and dried), what part of the system uses the most energy? 

 

Step 1: Estimate your product system’s biggest uses of energy. 

   Time Estimate: 1/2–2 hours

Calculate the energy use of your product’s main subsystems, using estimations of power use and time spent running. Use whatever means you wish to estimate this (measuring with a watt meter, researching online, looking up spec sheets for components from your BOM, etc.)  A few hints:

  • Include components that transform energy (e.g. from electricity to heat, or from AC to DC electricity).
  • Remember that whatever uses the most power may not use the most energy. For example, if a microwave oven uses 1,000 W of power to cook food, but only uses it for 6 minutes per day (thus causing an energy use of 100 Wh per day), but its clock and other systems use 5 W of power all 24 hours of the day (for an energy use of 120 Wh per day), then it uses more energy idling than cooking.
  • Your product may cause other things to use energy–even more than your product itself.  (For example, clothing uses no energy while being worn, but causes energy to be used by washing machines and perhaps dryers.)
  • If your product does not use energy during its useful life and doesn’t cause energy to be used by anything else, estimate what materials in the product cause the most “embodied energy” impacts. For example, aluminum has a high embodied energy because of the large amounts of processing energy required to refine it from ore.  (If you did an LCA, you can quickly estimate embodied energy by looking at CO2 emissions per material, as CO2 is generally a good proxy for energy use in traditional material extraction & processing.)

Finally, be careful with your time.  Digging into details like this will take as much time as you let it. This assignment is meant to only take a couple hours, so don’t worry about spending 30 hours making it perfect. 

 

Step 2: Estimate energy use per functional unit.

   Time Estimate: 10–30 minutes

Translate the above calculations into energy per unit of service. That is, take the calculations you made above and divide by the number of units of service the user gets from the product. For example:

  • If a microwave oven averages 220 Wh per day (see calculations above), and its service is measured in minutes of cooking food, its energy intensiveness per unit of service is (220 Wh/day) / (24 hrs/day) / (60 min/hr) = 0.15 Wh per minute of service for average use.  (A more sophisticated analysis would separate cooking energy and idling energy for different usage scenarios.)
  • If it takes 52,000 Wh of energy to mine and refine all the steel, glass, electronics, etc. to make the microwave, and its useful life is 10 years, its embodied energy per unit of service is (52,000 Wh) / (10 yrs) / (365 days/yr) / (24 hrs/day) / (60 min/hr) = .01 Wh per minute of service.

 

Step 3: Document your energy priorities.

   Time Estimate: 10–30 minutes
  • List the top three users of energy in your product’s whole system, in order (biggest energy user first).
  • For each of these energy users, show your math and your data sources. (e.g. “#1. Motor: uses 10W for an average of 5 hrs/day, for 50 Wh/day average. Power data from motor spec sheet, http://company-x-motor-spec-sheet.com, daily usage data from our interviews.”) 

 

 


 

Exercise   2

Brainstorm Energy Improvements

   Time Estimate: 2–5 hours

   Goal: Brainstorm ways to radically reduce your product’s energy use and energy impacts.

 

Here you’ll do two brainstorms: one for the amount of energy, one for the source of energy. 

 

Step 1: Brainstorm ways to reduce your product’s energy use by a factor of ten 

   Time Estimate: 30–60 minutes

Hold a brainstorm session, using the Rules of Brainstorming and whatever collaboration tools you prefer, to generate ideas for reducing your product’s energy use to 1/10th the energy it uses today. (Don’t limit yourself to factor-ten ideas–it is a brainstorm after all–but don’t be shy about radically re-envisioning the product. What need is the product fulfilling, and how else could that need be fulfilled?)

If your product doesn’t use energy itself but causes energy to be used by something else in its system (like clothing and a washer / dryer), brainstorm ways your product could reduce that energy use. If your product does not use energy during its useful life, and doesn’t cause energy to be used by something else in its system, then brainstorm ways in which its manufacturing or materials can use 1/10th as much energy.

  • Start with the Whole System Map you created for your product, to keep in mind all the components of the system, and how they connect to each other, and the product’s role in the larger system.
  • Have a good number of ideas (30+) to replace or change parts of the system that have high impacts.
  • Have at least one idea for every major component or step in the system.
  • Have at least six ideas that eliminate a step or component of your system. Eliminating multiple steps / components is even better. 

 

Step 2: Brainstorm clean energy sources to reduce the impacts of your product’s energy use by a factor of ten 

   Time Estimate: 30–60 minutes

Hold a brainstorm session, using the Rules of Brainstorming and whatever collaboration tools you prefer, to generate ideas for switching energy sources to reduce its environmental impacts to 1/10th the impacts it has today. (Once again, don’t limit yourself to factor-ten ideas, but don’t be shy about radically re-envisioning the product’s energy generation and storage systems.)  How could your product harvest free energy from heat, motion, fluid flow, light, or other phenomena happening around it?

As before, if your product doesn’t use energy itself but causes energy to be used by something else in its system, brainstorm ways you could switch that to clean energy. (Ideally ways your product could cause it, but if that’s not possible, you can think up ideas unrelated to your product.) If your product does not use energy during its useful life, and doesn’t cause energy to be used by something else in its system, then brainstorm ways in which its manufacturing or materials can switch to clean energy to have 1/10th the impact.

  • Start with the Whole System Map you created for your product, to keep in mind all the components of the system, and how they connect to each other, and the product’s role in the larger system.
  • Have a good number of ideas (30+) to replace or change parts of the system that have high impacts.
  • Have at least one idea to change / replace every major component or step in the product system.
  • Have at least six ideas that eliminate a step or component of your system. Eliminating multiple steps / components is even better. 

 

Step 3: Narrow down your brainstorm options to three or four winning ideas per brainstorm

   Time Estimate: 5–30 minutes

Using common sense or whatever tools you desire, narrow down each of your two brainstorms to just three or four candidates each. In addition to judging them by energy impacts, use considerations from your Design Brief to rule out options that don’t meet business criteria such as cost or usability. 

 

Step 4: Estimate the total energy impacts for each winning option, and choose the best idea from each brainstorm

   Time Estimate: 20–60 minutes

If your product uses energy during its life (or causes significant energy use in its system):

  • Estimate the total lifetime energy use per functional unit of each of the winning ideas you’ve chosen, from both brainstorms.
  • Using LCA or other estimation tool, calculate the total lifetime impacts of that energy use per functional unit, for each idea. You do not need to do a full LCA, just record the impacts for energy use.

If your product does not use energy during its life:

  • Use LCA or other tool to estimate the embodied CO2 impacts per functional unit of your new ideas. Include the whole product in the estimated LCAs, as you’ll likely be replacing several different materials.

 

Step 5: Choose one final idea to move forward with, and illustrate it

   Time Estimate: 5–30 minutes
  • Choose one winning idea, based on the estimated impacts and your other design brief priorities. (You could also decide to pursue multiple winners, or combine ideas.)
  • Illustrate the final idea (rough sketch or fancy rendering) to clearly convey its energy improvement, and why it’s a compelling design. 

 

Step 6: Document your decision and brainstorms

   Time Estimate: 20–60 minutes
  • Create a PDF with a short description and illustration of the winning design(s), and the reasons for your choice.
  • Show both of your brainstorms, making it clear that you had at least one idea for every part of the system, and many ideas that skipped steps in the system.
  • Show the illustration of the winning design(s).
  • Succinctly describe the winning design, either as annotations to the illustration or as a standalone sentence or two. Describe why it is the best of all your new ideas.
  • Show your estimates of total lifetime energy use per functional unit (or, for products that don’t use energy, embodied CO2 impacts per functional unit), both for the final winning idea and all the other ideas you ran numbers for. The ideas that didn’t get chosen as the final winner don’t need descriptions, but at least make their titles suggest what they are.
  • Show your math for all the above estimates.

State how much you expect the winning design to improve ecological impact compared to the original design. 

 

 


Checklist for Self-Assessment

To score your success on this exercise, see if you…

  1. Energy amount brainstorm
  2. Energy source brainstorm
  3. Had 30+ ideas for both the energy amount and energy source brainstorms
  4. Had at least one idea for every major component or step in the system, for both brainstorms.
  5. Had at least six ideas that eliminate a step or component of the system, for both brainstorms.
  6. Chose 3 – 4 winning ideas per brainstorm.
  7. Calculated improved impact of all winning ideas.
  8. Illustrated final idea(s).
  9. Described final idea(s).

 

 

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