PEV – Personal Energy Value in Environmental Calculations

Inventing Ways to Help us Understand – Part 1

We should factor in our time with respect to energy calculations.  For instance: our time should be a factor when we are riding a bike to work rather than driving.  Another example is if we turn off our computer and then later have to wait two minutes to turn it on.  We might even examine our past-times like what is it costing to do that Sudoko! (Yikes… not to put a damper on our relax time!)

The proposition is that we require energy to live and that we waste this energy by wasting our time.  So we need an amount that we can attribute to our personal energy.  We call this:

PEV = Personal Energy Value

It is comprised of three parts:

  • Sustenance Energy (Electricity, Gas, Food)
  • Environmental Solution Energy (Originate, Promote, Influence)
  • Cultural Worth Energy (Creation vs Consumption)

Before going into details of PEV – let us look at turning off and on the computer as an example.  It might be that we can do something else while we wait for the computer to come on but I suspect that the majority of us just sit there in a daze or worse yet, grumble that we are having to wait!


Imagine that it takes a minute to start the computer and that the computer uses 50W (Watts) in sleep mode.  I am on my computer about 6 hours a day and might go to and from my computer 10 times.

By not turning off the computer each time we have:
18h * 50W = 900Wh = .9 kWh per day
By the way, a 40W bulb running all day is roughly 1 kWh.
If it takes 5000W to support my existence at my current lifestyle
I am waiting 10 minutes a day so this takes:
5000W * 10/60 = 833Wh = .8 kWh per day
See PEV Standard Unit below for where we got 5000W

So there is almost a direct trade off with these calculations.  A compromise I suppose would be to turn the computer off at night.


Here is where I got the 5000W to keep me going. It might be a little backwards but I used a footprint calculator to get yearly CO2.  These calculators factor in a series of things but I just chose Electricity, Gas and Food leaving out travel and consumer purchases. I then used a conversion chart to get kWh:

Electricity (yearly from CO2 calculator)

1 kWh = 0.537 kg CO2 (conversion)
2.5 tonnes CO2 * 1000 kg per tonne / 0.537 kg CO2 per kWh
= 4655.5 kWh / year
= 18.2 kWh / day
= 758 Watts

Gas (yearly from CO2 calculator)

1 kWh = 0.185 kg CO2 (conversion)
3.5 tonnes CO2 * 1000 kg per tonne / 0.185 kg CO2 per kWh
= 18919 kWh / year
= 73.9 kWh / day
= 3079 Watts

Food (yearly from CO2 calculator)

1 kWh = 0.268 kg CO2 (conversion)
2.0 tonnes CO2 * 1000 kg per tonne / 0.268 kg CO2 per kWh
= 7463 kWh / year
= 29.2 kWh / day
= 1215 Watts

Adding up the Watts above, an average person might use:

= 120 kWh / day
= 5 kWh / hour
= 5000 Watts
= 50 100 Watt bulbs

Hmmm… maybe – I need some verification of these calculations and it will vary per person.  But it would be good to know and really this article is about moving towards calculations like these as opposed to providing hard and fast numbers.

We will call this amount our PEV Standard Unit

PEV SU = 5000 Watts

But my life must be worth something more than just the energy to keep me going!


You can, in a sense, add more environmental importance to your time if you spend time originating and or promoting environmental solutions.  Perhaps what matters most is whether are you influencing people – in a positive way ;-).

How this factors in is quite difficult to tell so we can almost treat this as an incentive for your consciousness.  But I think the incentive will work in the positive in the end as long as you are honest about it.

So we add this to our PEV as follows:

add 0.1 times the PEV SU for each item that applies to you:

  • research and apply environmental solutions
  • lead by example through environmental solutions
  • encourage friends and family to be conscious
  • attend talks about environmental solutions
  • blog about environmental solutions
  • originate environmental solutions
  • give talks about environmental solutions
  • rally for environmental causes
  • donate to environmental causes
  • create or manage environmental policy

Multiply this number by percentage perceived success in influencing others

I can check about six of these with an influence of 50%

.6 for the checks and .5 for the influence:
My PEV = 5000 W (original) + .6 * 5000 W * .5 = 6500 W


If we are wasting our time, is this a detriment to culture?  It is obviously impossible to be exact here but again, our time is worth something.  This simple calculation is perhaps a token.  Of course, we should be careful in valuing our individual self above the needs of our environment. But, without culture, there would be less motivation for saving the world.  So if you contribute then you encourage people to want to find and implement solutions.

What percentage of your waking time do you create versus consume? Call this the cultural factor. Multiply half the PEV SU x Cultural Factor and add it to the PEV.

My PEV = 6500 W + .8 (Cultural Factor) * 5000 W / 2 = 8500 W


Now my computer calculation becomes:

If I have 8500 W of Personal Energy (PEV) and
I am waiting 10 minutes a day for my computer then this is worth:
8500W * 10/60 = 1417Wh = 1.4 kWh per day

This is more than .9 kWh per day if I turn off and on the computer so I should leave my computer on. If we leave off the Cultural Worth, then this is 1.1 kWh per day and is still worth it to leave the computer on (turning off at night is good though).

We have a few levels of calculations here but certainly for a few – the calculations are direct – for others, they are less direct.  It does take energy to support us so at least factor the PEV Standard Unit into your calculations.  You are welcome to try and determine your own “Standard Unit” or a better average standard unit – let us know.  I would argue that the other two factors to personal energy – that of Environmental Influence and Cultural Worth should also be considered.

If you work on a Sudoko for half an hour that is taking the following:

5000W * 30/60 = 2.5 kWh just using the PEV SU.
This would be 4.3 kWh using the extended PEV for me.

To put this in perspective:

.01 kWh – a charger per day
.5 hWh – shipping food to person per day
.5 kWh – computer standby all day

1 kWh – running a 40W light bulb all day
1 kWh – to drive 1 km (100 km in electric car)
3 kWh – our body uses per day
4 kWh – computer active all day

This article uses “back of the envelope” calculations.  The point really is that if done correctly, this system can lead to better understanding the choices and better answers! By no means am I trying to dispute that caring for the environment is wrong – we might be trying to help but without full data, we could be making the wrong decisions.

For example, the chart below shows car driving being favoured over biking when taking into consideration the feeding of the cyclist to address their energy usage. Click the chart to try the calculations.  One thing to look for is that I changed the selection from a smaller person, increased the speed of the cyclist and adjusted to better mpg on the car.   You might argue that there is the environmental cost of manufacturing the car but there are calculations that show this cost to be negligible over the life of the car.  You might say, what about pollution… this calculation takes pollution into account.  The calculation really is only part of the suggested PEV – and even just part of the PEV SU.  There is an issue here in that the PEV does not take into account activeness or non activeness.  That could be improved on.


Further reading and partial references…



  1. It is my understanding that the environmental cost of manufacturing a car is enormous. I’ve heard that the amount of oil required to assemble one Toyota Prius is more than you would ever use during the life of it.

  2. I just saw this briefly in the bottom of the bicycle link above –

    In any event, Chris Goodall, who wrote a similar article to this one, writes: “These numbers [e.g., the energy required to produce a car] are not enough to remotely affect the conclusion that car travel is less carbon intensive than walking, if the walker replaces lost energy with animal products.”

    He says that making a car produces 3 tons of carbon. Over a 200,000-mile life, that’s a 0.033 lbs. of carbon per mile. It’s not significant.

    Goodall also sums up my frustration with the reception to our articles very well: “I was extremely naive not to realize that the analysis would be perceived as an encouragement to drivers. I didn’t intend it to be read that way. My purpose was to draw attention to the carbon intensity of modern food production, particularly of meat.”

    • So that would be somewhere around .001 kWh per mile (1/1000 the gas) if those numbers are correct. I suspect that even if we look at the PEV for each person involved in making the car – if a calculation like that was not made in the 3 tons – then the PEV would probably not be significant across the car’s life.

      Just note again that these numbers change to favor walking or biking if you do not eat meat and particular beef it seems. But there is still the aspect of cultural worth – as in, our time if we advance culture is worth something.

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