Air Handling Unit, Outside Air, Exhaust Air, Return Air and Energy Recovery Unit

Posted by PITHOCRATES - March 27th, 2013

Technology 101

Things that Absorb Energy can Cool Things Down and Things that Radiate Energy can Warm Things Up

When two different temperatures come into contact with each other they try to reach equilibrium.  The warmer temperature cools down.  And the cooler temperature warms up.  If you drop some ice cubes into a glass of soda at room temperature the warm soda cools down.  The ice cubes warm up.  And melt.  When there is no more ice to melt the temperature of the soda rises again.  Until it reaches the ambient room temperature.  The normal unheated or un-cooled temperature in the surrounding space.  As the soda and the air in the room reach equilibrium.

When two temperatures come into contact with each other what happens depends on the available energy.  Higher temperatures have more energy.  Lower temperatures have less energy.  For heat is energy.  Things that absorb energy can cool things down.  Things that radiate energy can warm things up.  And this is the basis of our heating and cooling systems in our buildings and homes.

Boilers burn fuel to heat water.  A furnace burns fuel to heat air.  The heated water temperature and heated air temperature is warmer than the temperature you set on your thermostat.  When this very hot water/air circulates through a house or building it comes into contact with the cooler air.  As they come into contact with each other they bring the air in the space up to a comfortable room temperature.  Above the unheated ambient temperature.  But below the very hot temperature of the heating hot water or heated air temperature.

Heating and Cooling Buildings consume up to Half of all Energy on the Planet

Large buildings have air handling units (AHU) that ventilate, heat and cool the building’s air.  They’re big boxes (some big enough for grown men to walk in) with filter sections to clean the air.  Coil sections that heat or cool the air as it blows through these coils.  A supply and a return fan to blow air into the building via a network of air ducts.  And to suck air out of the building through another network of air ducts.  And a series of dampers (outside air, exhaust air and return air).

To keep the air quality suitable for humans we have to exhaust the breath we exhale from the building.  And replace it with fresh air from outside of the building.  This is what the dampers are for.  The amount they open and close adjusts the amount of outside air the AHU pulls into the building.  The amount of the air it exhausts from the building.  And the amount of air it recirculates within the building.  Elaborate computer control systems carefully adjust these damper positions.  For the amount of moving air has to balance.  If you exhaust less you have to recirculate more.  Otherwise you may have dangerous high pressures build up that can damage the system.

It takes a lot of energy to do this.  Buildings consume up to half of all energy on the planet.  And heating and cooling buildings is a big reason why.  Because it take a lot of energy to raise or lower a building’s air temperature.  And keeping the air safe for humans to breathe adds to that large energy consumption.  If you stand outside next to an exhaust air damper you can understand why.  If it’s winter time the exhausted air is toasty warm.  If it’s summer time the exhausted air is refreshingly cool.

An Energy Recovery Wheel is a Circular Honeycomb Matrix that Rotates through both the Outside & Exhaust Air Ducts

In the winter large volumes of gas fire boilers to heat water.  Electric water pumps send this water throughout the building.  Into baseboard convection heaters under exterior windows to wash this cold glass with warm air.  And into the heating coils on AHUs.  Powerful electric supply and return fans blow air through those heating coils and throughout the building.  After traveling through the supply air ductwork, out of the supply air ductwork and into the open air, back into the return air ductwork and back to the AHU much of this air exhausts out of the building.  That returning air is not as warm as the supply air coming off of the heating coil.  But it is still warm.  And exhausting it out of the building dumps a lot of energy out of the building that requires new energy to heat very cold outside air to replace it.  The more air you recirculate the less money it costs to heat the building.  But you can only recirculate air so long before you compromise the quality of indoor air.  So you eventually have to exhaust heated air and pull in more unheated outside air.

Enter the heat recovery unit.  Or energy recovery unit.  There are different names.  And different technologies.  But they do pretty much the same thing.  They recover the energy in the exhaust air BEFORE it leaves the building.  And transfers it to the outside air coming into the building.  To understand how this works think of the outside air duct and the exhaust air duct running side by side.  With the air moving in opposite directions.  Like a two-lane highway.  These sections of duct run between the AHU and the outside air and exhaust air dampers.  It is in this section of ductwork where we put an energy recovery unit.  Like an energy recovery wheel.  A circular honeycomb matrix that slowly rotates through both ducts.  Half of the wheel is in the outside air duct.  Half of the wheel is in the exhaust air duct.  As exhaust air blows through the honeycomb matrix it absorbs heat (i.e., energy) from the exhaust air stream.  As that section of the wheel rotates into the outside air duct the unheated outside air blows through the now warm honeycomb matrix.  Where the unheated air absorbs the energy from the wheel.  Warming it slightly so the AHU doesn’t have use as much energy to heat outside air.  It works similarly with air conditioned air.

Many of us no doubt heard our mother yell, “Shut the door.  You’re letting all of the heat out.”  For whenever you open a door heated air will vent out and cold air will migrate in.  Making it cooler for awhile until the furnace can bring the temperature back up.  It’s similar with commercial buildings.  Which is why a lot of them have revolving doors.  So there is always an airlock between the heated/cooled air inside and the air outside.  But engineers do something else to keep the cold/hot/humid air outside when people open doors.  They design the AHU control system to maintain a higher pressure inside the building than there is outside of the building.  So when people open doors air blows out.  Not in.  This keeps cold air from leaking into the building.  Allowing people to work comfortably near these doors without getting a cold blast of air whenever they open.  It allows people to work along exterior windows and walls without feeling any cold drafts.  And it also helps to keep any bad smells from outside getting into the building.

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Macroeconomic Disequilibrium

Posted by PITHOCRATES - September 24th, 2012

Economics 101

In the Barter System we Traded our Goods and Services for the Goods and Services of Others

Money.  It’s not what most people think it is.  It’s not what most politicians think it is.  Or their Keynesian economists.  They think it’s wealth.  That it has value.  But it doesn’t.  It is a temporary storage of value.  A medium of exchange.  And that alone.  Something that we created to make economic trades easier and more efficient.  And it’s those things we trade that have value.  The things that actually make wealth.  Not the money we trade for these things.

In our first economic exchanges there was no money.  Yet there were economic exchanges.  Of goods and services.  That’s right, there was economic activity before money.  People with talent (i.e., human capital) made things, grew things or did things.  They traded this talent with the talent of other people.  Other people with human capital.  Who made things, grew things or did things.  Who sought each other out.  To trade their goods and services for the goods and services of others.  Which you could only do if you had talent yourself.

This is the barter system.  Trading goods and services for goods and services.  Without using money.  Which meant you only had what you could do for yourself.  And the things you could trade for.  If you could find people that wanted what you had.  Which was the great drawback of the barter system.  The search costs.  The time and effort it took to find the people who had what you wanted.  And who wanted what you had.  It proved to be such an inefficient way to make economic transactions that they needed to come up with a better way.  And they did.

The Larger the Wheat Crop the Greater the Inflation and the Higher the Prices paid in Wheat

They found something to temporarily hold the value of their goods and services.  Money.  Something that held value long enough for people to trade their goods and services for it.  Which they then traded for the goods and services they wanted.  Greatly decreasing search costs.  Because you didn’t have to find someone who had what you wanted while having what they wanted.  You just had to take a sack of wheat (or something else that was valuable that other people would want) to market.  When you found what you wanted you simply paid an amount of wheat for what you wanted to buy.  Saving valuable time that you could put to better use.  Producing the goods or services your particular talent provided.

Using wheat for money is an example of commodity money.  Something that has intrinsic value.  You could use it as money and trade it for other goods and services.  Or you could use it to make bread.  Which is what gives it intrinsic value.  Everyone needs to eat.  And bread being the staple of life wheat was very, very valuable.  For back then famine was a real thing.  While living through the winter was not a sure thing.  So the value of wheat was life itself.  The more you had the less likely you would starve to death.  Especially after a bad growing season.  When those with wheat could trade it for a lot of other stuff.  But if it was a year with a bumper crop, well, that was another story.

If farmers flood the market with wheat because of an exceptional growing season then the value for each sack of wheat isn’t worth as much as it used to be.  Because there is just so much of it around.  Losing some of its intrinsic value.  Meaning that it won’t trade for as much as it once did.  The price of wheat falls.  As well as the value of money.  In other words, the bumper crop of wheat depreciated the value of wheat.  That is, the inflation of the wheat supply depreciated the value of the commodity money (wheat).  If the wheat crop was twice as large it would lose half of its value.  Such that it would take two sacks of wheat to buy what one sack once bought.  So the larger the wheat crop the greater the inflation and the higher the prices (except for wheat, of course).  On the other hand if a fire wipes out a civilization’s granary it will contract the wheat supply.  Making it more valuable (because there is less of it around).  Causing prices to fall (except for wheat, of course).  The greater the contraction (or deflation) of the wheat supply the greater the appreciation of the commodity money (wheat).  And the greater prices fall.  Because a little of it can buy a lot more than it once did.

Keynesian Expansionary Monetary Policy has only Disrupted Normal Market Forces

Creating a bumper crop of wheat is not easy.  Unlike printing fiat money.  It takes a lot of work to plow the additional acreage.  It takes additional seed.  Sowing.  Weeding.  Etc.  Which is why commodity money works so well.  Whether it’s growing wheat.  Or mining a precious metal like gold.  It is not easy or cheap to inflate.  Unlike printing fiat money.  Which is why people were so willing to accept it for payment.  For it was a relative constant.  They could accept it without fear of having to spend it quickly before it lost its value.  This brought stability to the markets.  And let the automatic price system match supply to the demand of goods and services.  If things were in high demand they would command a high price.  That high price would encourage others to bring more of those things to market.  If things were not in high demand their prices would fall.  And fewer people would bring them to market.  When supply equaled demand the market was in equilibrium.

Prices provide market signals.  They tell suppliers what the market wants more of.  And what the market wants less of.  That is, if there is a stable money supply.  Because this automatic price system doesn’t work so well during times of inflation.  Why?  Because during inflation prices rise.  Providing a signal to suppliers.  Only it’s a false signal.  For it’s not demand raising prices.  It’s a depreciated currency raising prices.  Causing some suppliers to increase production even though there is no increase in demand.  So they will expand production.  Hire more people.  And put more goods into the market place.  That no one will buy.  While inflation raises prices everywhere in the market.  Increasing the cost of doing business.  Which raises prices throughout the economy.  Because consumers are paying higher prices they cannot buy as much as they once did.  So all that new production ends up sitting in wholesale inventories.  As inventories swell the wholesalers cut back their orders.  And their suppliers, faced with falling orders, have to cut back.  Laying off employees.  And shuttering facilities.  All because inflation sent false signals and disrupted market equilibrium.

This is something the Keynesians don’t understand.  Or refuse to understand.  They believe they can control the economy simply by continuously inflating the money supply.  By just printing more fiat dollars.  As if the value was in the money.  And not the things (or services) of value we create with our human capital.  Economic activity is not about buying things with money.  It’s about using money to efficiently trade the things we make or do with our talent.  Inflating the money supply doesn’t create new value.  It just raises the price (in dollars) of our talents.  Which is why Keynesian expansionary monetary policy has been such a failure.  For their macroeconomic policies only disrupt normal market forces.  Which result in a macroeconomic disequilibrium.  Such as raising production in the face of falling demand.  Because of false price signals caused by inflation.  Which will only bring on an even more severe recession to restore that market equilibrium.  And the longer they try to prevent this correction through inflationary actions the longer and more severe the recession will be.

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