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# Is it more energy efficient to take the stairs or the lift?

Our world is changing. In this age of advancement and connection there is something growing ever more important, uniting all countries, climate change. Each one of us has a part to play in how we tackle this global issue and a number of small acts will turn the tide.

So today I am going to tackle this world problem by answering the irreverent question: "Is it more energy efficient to take the stairs instead of the lift?" What could be more pressing?

So, both the lift and the stairs require energy seeing as we are moving a body of mass through vertical space. For the lift, this energy is provided by a power source, most likely in the UK to be carbon based. For the stairs, the human body with all its miracles is providing the power through the calorific value of the food that has been consumed.

Energy usage for food consumption is a massive hidden cost. The financial cost may be low, but the produce had to be grown or reared on land that was probably forest, then picked, prepared, packaged, distributed, sold, cooked and eaten all of which probably incurred some cost to the environment.

To try and make my calculations simpler I'm going to focus only on the energy needed to produce different varieties of food in kWH and how much energy a lift needs in the same metric.

So first, what foods do I have values for? A quick search by your favourite search engine will give you some idea. I used the data available here. Next we need to know how much of that food we need in order to climb the stairs. You need approx 0.17 calories per stair (up) and the OVO office in London has 54 stairs (I counted). So using the number of calories you get from the food, we have a fairly good idea of the impact of me researching this article.

Energy needed to make 1lb Calories per lb Amount of food needed for 54 stairs Amount of energy needed to make food for 54 stairs
Corn [1] 0.43 390 2.35% 0.010
Milk [2] 0.75 291 3.15% 0.024
Apples [3] 1.67 216 4.25% 0.071
Eggs [4] 4 650 1.41% 0.056
Chicken [5] 4.4 573 1.60% 0.070
Cheese [2] 6.75 1824 0.50% 0.034
Pork [6] 12.6 480 1.91% 0.241
Beef [7] 31.5 1176 0.78% 0.246
Average 7.7625 700 1.31% 0.102

On to the lift, turns out they are more interesting than I would have thought. The parameters needed to accurately calculate how much energy our lift uses would take longer than my lunch break to solve. So I used this handy lift energy consumption calculator to get an estimate for energy consumption for the year. Then maths to the max to get consumption per day and a guesstimate of 200 trips a day to get the value per trip.

Energy to run the elevator for a year 7855
Per day 21.521
Number of trips a day 200
Per trip 0.108

So as the numbers now show, if you eat meat as your source of stair fuel, you'd be better off taking the lift. If you eat a vegetarian or vegan diet you can take the stairs. If you eat a balanced diet of all the food stuffs I have data for, also the stairs!

Obviously all this time would be saved if you had a Green Energy Plan from OVO. Just saying.

Credit to Ed Conolly for asking the original question and to spreadsheets, what a blast it has been.

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