# Not a simulation question, but need help looking for vendor/ product developer for

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Joined: 2011-09-30
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Neeraj,

An interesting application. Although I cannot help you with the piezoelectric devices you seek, I do know a very reliable manufacturer of whoopee cushions. If these could somehow be connected into a turbine generator system, then I?m sure you could generate an equivalent amount of power. Other benefits include:

? With the deluxe ?auto inflating? range, the cushions would remove air from the room with every footfall ? energy free ventilation!

? Whoopee cushion technology is tried and tested, having been developed over the last 80 years.

? Zero ODP & GWP

? Fun, and a possible lasting attraction encouraging users back to the building for years to come!

Best regards

Chris Yates

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Neeraj,

I apologise for my response. I do not wish it to reflect in any way on the professionalism and help that this list endeavours to supply. I was out of order, sorry.

I seek to supply a more appropriate reply (and in doing so open myself to ridicule because there are probably a couple of mistakes in my working out!). Here goes:

The feasibility of a piezoelectric system implemented as floor tiles does seem to fly in the face of my understanding of Newton, Force and Work.

Average person has a mass of, say, 70kg.

Force exerted by both feet, therefore = mass x gravity = 70 x 9.81 = 686.7Newtons or 343 per foot

For the transfer of energy with every foot fall Work must be done to the tile. That means it must undertake some deflection. The resulting work transferred to the tile in Joules would be similar to the elastic potential energy equation: EPE = ? x kX2

Let?s say the tile deflects 1mm under one foot. Therefore the spring constant k for the tile would be 343350N/m and EPE of the tile whilst stood on would be 0.172 Joules.

This is just EPE stored by the tile whilst loaded. The tile will probably consist of the piezo device and a substrate which the energy will dissipate over. Let?s be generous and assume 20% of that work is converted to electrical energy. We are now talking about 0.034 Joules per foot fall. The rest will escape as heat. Considering a human metabolism whilst walking will be of the order of 120 Watts plus (Watts = Joules / second) the energy recovered through floor tiles would be minimal.

I hope this is useful.

Chris

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Neeraj,

Pavegen Systems in the UK are in the process of commercialising such a
product: http://www.pavegensystems.com

There's no technical info on here though and, like Chris, I would be
pretty sceptical that the contribution from this would even register
against your overall building consumption. If you find out otherwise do
let us know!

Phil

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Lets try to keep the BDLG-SIM mailing list relevant and only
post messages related to building energy simulation. Here
are the guidelines:

http://onebuilding.org/guidelines.html

If you want to post a message outside these guidelines,

Jason

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Ha, that is great. Thank you, what a fine way to start a Monday. Neeraj, if you are seriously looking into getting energy from people's fancy footwork I would suggest looking into the (nite) club's that are putting it in their dance floors. You may be able to find a manufacturer.

Good looks, guys! Before you know it we will all be nothing more than hamsters on a wheel.

Kevin

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They've installed piezo electric dance floors in London, Rotterdam and
San Francisco. See the below link for details of the one in London.

http://inhabitat.com/2008/07/16/green-a-go-go-at-londons-first-eco-disco
/

Unfortunately I can't find the name of the manufacturer or guarantee the
quality of the dancing.

Dan.

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Whoops, (not whoopee), the talk of professionalism. Allow me to digress, I don't think we are hamsters nor should we be compared to those loveable furry creatures.

Thank you.

Kevin

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I once thought of opening a gym where each piece of equipment generated
electricity. (Bikes, stair masters, bench press).

I started by calculating the best case, the stationary bike.

Long story short. People are weak. You save far more energy by turning off
the light.

"The current record holder for the Hour Record is Ondrej Sosenka and the
website BikeCult.com has an estimate of his average wattage during his Hour
Record at 430 Watts! If Ondrej's bike were attached to a bicycle generator
and it was super efficient, Ondrej would have been generating enough power to
light up 7 60-Watt light bulbs! Since I pay about 10 cents/kWh, if I were
to pay Ondrej for the energy he produced over the hour he was pedaling he
would have almost earned a whole nickel (430 Watts * 1 hour = 430 Watt-hours
= .43 kWh)!"

I don't see any way a dance floor could produce enough energy to power the a
couple of 1000 Watt speakers.

If it is feasible please send the information (as an engineer I'd like to see
the numbers.)

In building simulation, I would account for the heat a person produces, but
not the electricity.

John Eurek

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1.
The cushioning effect may give the tile floor a softer feel, perhaps like walking on a thin carpet? Just a thought.
2.
I see some difficult technical issues to be resolved, however, like sand and dirt (and sometimes liquids) between the moving plates. Perhaps a flexible impervious cover (sealant) could be found that will last a few years.
3.
The idea is truly interesting and worth looking into, especially for floors with very heavy foot traffic such as airports and some public buildings. How about the New York Stock Exchange (Harness some of that energy! Might mitigate the need for public power for the entire city)?

Glenn Haynes,
Middletown, CT

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Here is an attached link for such a system. (please note I am not promoting it I am just aware of it's existence should people be interested)

Home Pavegen Systems www.pavegensystems.co.uk

Regards

Michael Keohane

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I just seem to remember that small issue that the Millennium Bridge in
London suffered from, harmonic resonance. A series of these things mounted
down the pavement and everyone walking in unison, and before we know it,
pedestrians will be suffering from sick pavement syndrome. Nice simulation
project, reckon that?s a real earner ;-) Arup didn?t too badly out of the
Millennium Bridge situation, even though it was one of their own making.

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