Once you have decided on the air conditioning system for your home you will probably be interested to know how much it will cost to run. Actual running costs depend on the size of the unit and how much time it is operating at full load and your local electricity cost. The examples below will give you an idea of the maximum cost per hour for heating and cooling. In the product information you have received there will be several numbers that will help you understand how much it will be to run the system for both heating and cooling. If the data sheet has Power Input figure in kW (not the heating or cooling capacity of the unit) you simply multiply this number by your local energy cost in kWh (kilowatt hours) to give you a running cost in cents. If the input power figure is not given you will need to divide the Cooling Capacity figure by the EER figure and then multiply this by your local energy cost. e.g. 1 Input power rating for a 6.0kW wall hung split system is 1.84kW.

Multiply this by your local electricity cost (varies quite bit within Australia so check your latest electricity bill.) say 25* cents per kilowatt hour. e.g.2 Running cost = 1.84 X 25 = 46 cents per hour For the same unit the Cooling Capacity is 6.0 divided by EER of 3.26 = 1.84 1.84 X 25* cents = 46 cents per hour. For heating use the heating capacity and the COP figures instead of cooling capacity and EER. e.g. 3 For this unit the Heating capacity is 7.0 and the COP is 3.41 7.0 divided by 3.41= 2.05 multiply this by your energy cost (25c*) and you get a heating mode running cost of 51.25 cents per hour. * Please note the 25 cents per kilowatt hour amount is used purely to show you how the calculation works. Actual rates vary considerably both above and below 25cents and you should consult your most recent electricity bill or your electricity supplier for your actual electricity tariff.Getty ImagesAn F-16 readies for takeoff. Last week, Battleland bemoaned the increasing difficulty finding cost-per-flight-hour data for U.S. military aircraft.

In a flash, longtime defense watcher – from a perch on Capitol Hill, as well as a stint at the Government Accountability Office – Winslow Wheeler piped up to say he recently sought, and got, such data from the Air Force comptroller’s office.ac unit not running He adds that he has tried to get similar data from the Navy, without luck. central air conditioner prices and installationWhat’s up with that, Admiral Kirby?how much do new ac units cost The Air Force provided Wheeler with cost-per-flight-hour for dozens of aircraft. Here’s a sample of what it costs to keep these Air Force aircraft airborne for one hour last year (the so-called “ownership” cost-per-flight-hour, which includes modifications):

A-10C Warthog Attack Plane — $17,716 AC-130U Spooky Gunship — $45,986 B-1B Lancer Bomber — $57,807 B-2A Spirit Stealth Bomber — $169,313 B-52H Stratofortress Bomber — $69,708 C-130J Hercules Cargo Plane — $14,014 C-17 Globemaster Cargo Plane — $23,811 C-20B VIP Plane (Senior Pentagon Officials) — $32,212 C-32A VIP Plane (Vice President, Cabinet Officers) — $42,936 C-5B Galaxy Cargo Plane — $78,817 CV-22B Osprey Tilt-Rotor — $83,256 E-3B Sentry AWACS Radar Plane — $39,587 E-4B Flying Headquarters — $163,485 F-15C Eagle Fighter — $41,921 F-16C Viper Fighter — $22,514 F-22A Raptor Fighter — $68,362 HH-60G Pave Hawk Helicopter — $24,475 KC-10A Extender Tanker — $21,170 MC-130H Combat Talon II Special Operations Plane — $32,752 MQ-1B Predator Drone — $3,679 MQ-9A Reaper Drone — $4,762 RQ-4B Global Hawk Drone — $49,089 T-38C Talon Jet Trainer — $9,355

T-6A Texan II Turboprop Trainer — $2,235 U-2 Dragon Lady Spy Plane — $30,813 UH-1N Huey Helicopter — $13,634 VC-25A Air Force One — $161,591It’s an age old question: What is more fuel efficient when driving a car and trying to keep cool, having the air conditioning on or the windows down?For years people have tussled over which uses more fuel, with most of the opinion that having the windows down is better up to a certain speed, when drivers should then switch to air conditioning.However, studies suggest that having the windows down could be the best solution at all speeds - and the air conditioning never needs to be turned on. Air conditioning versus rolling the windows down: which makes your car more fuel efficient? Previously it had been thought it was better to switch to air conditioning at higher speeds, but new research suggests it might always be better to roll the windows down and never touch the air conditioning button Basic physics suggests that air conditioning should perform better at higher speeds.

A car’s air conditioner is essentially powered by the engine - most cars have a compressor system driven by a belt.ENERGY-EFFICIENT DRIVINGSome people around the world known as ‘hypermilers’ consider themselves professionals when it comes to maximising car fuel efficiency.They do this through a number of methods that may seem slightly odd to some.This includes keeping the windows up and the air conditioning off.But some go to rather more extreme measures, such as wearing ice vests to keep cool.They are also known to tailgate large vehicles to get in their slipstream and keep fuel use down.Others do their best to avoid braking at all costs or even turn off their engine while moving. When driving at slower speeds, the small but continuous effect of having the air conditioning on means the car’s engine works harder, and thus more fuel is used. At speeds of 70 miles (110 km) per hour on a motorway, however, it is often said that the effect of air conditioning on fuel efficiency is negligible when compared to having windows open.

Depending on speed, having air conditioning on at a medium level can reduce the fuel efficiency of a car down by up to 10 per cent, according to Vox.At slower speeds it makes more sense to have the windows open to cool the car down - air easily circulates from outside to inside the car without causing too much drag.As speed is increased, however, the air resistance on the car also increases, meaning the engine has to work harder to maintain the car’s speed down the road as it becomes less aerodynamic.So, at higher speeds air conditioning is surely the winner - at least, that’s what was previously thought.But new research by Vox suggests this is not the case. A 2004 study by the Society of Automobile Engineers found that Sedans used more fuel when air conditioning was on than when windows were down. Note the axis on the left is gallons per mile, so a higher number is worse performing As a car's speed increases, so too does its air resistance. A car travelling at 70 miles per hour experiences four times as much drag as one travelling at 35 miles per hour.

This might suggest it is better to have the windows up, but research shows that air conditioning is worse for fuel efficiency even at these speeds Taking a look at previous studies, they found that it was actually more efficient to have the windows down for any speed expected on a road.In 2004, for example, the Society of Automobile Engineers found that both SUVs and Sedans were considerably less efficient at all speeds up to 70 miles (110 kilometres) per hour when using air conditioning over having the windows down.A test by popular American TV show Mythbusters, meanwhile, found similar results.This is despite the fact that drag doubles as speed increases - for example, a car travelling at 70 miles per hour will have twice as much force pushing against it than one travelling at 35 miles per hour.The reason is that air conditioning eats up more fuel that previously thought, while the effects of drag by having a window open are not as bad as most think.So it seems the solution to being both fuel efficient and keeping cool as the weather heats up might be to leave the air conditioning off, and crank the window open just a bit.