This topic has been thoroughly researched, indeed: Condensor Shading . They conclude that any savings produced by localized HVAC condenser shading are modest, <3%, or even less. Much more important is the effect of vertical and horizontal air blockage. I have currently been recommending to my clients the following: zero vertical impedement for 20 feet, two feet from house, two feet from fences or bushes, five feet from any other condensors. I hope this information is helpful to you!
I was given a report a handful of years ago by our coating distributor in Texas. He gave me the following information.
His neighbor had an ac unit with the condenser on the outside at ground level. Two pipes ran up the wall to attic floor level, made a 90 into the attic. For years the neighbor left the pipes bare, bare metal. H e at some point had wrapped them with foam pipe insulation. He had noticed no improvement in the air temperature or his electric bill.
Our guy. Joe Merrill, suggested they remove the foam and coat the pipes with our radiant barrier coating and see what happens. They did that and the owner said he and his wife felt it made a difference in the temperature of the house. They were happy and it was left like that.
No exact temperature readings were taken and I never heard if there was any noticeable difference in the electric bill. I wish I could find out more particulars but Joe passed away in early 2013.
An effective radiant barrier material provides a shading effect. Any time yuou can provide shade or a shading effect on outside cooling equipment, absolutely it is going to alloow that equipment to operate more efficiently.
One must also be aware that EVERYTHING around a building absorbs the sun's radiation during daylight hours. Those 'things' then radiate that heat out towards the cooling equipment that it must overcome, even in the shade of a house, tree, etc. AND those things will still radiate heat in all directions after the sun goes down.
I recall a large hospital in Porterville, CA. On one of their 3 levels of roof, you could hardly see the roof because of the ductwork on top. They had spent a fortune with a machine shop that mader, basically, oversize galvanized shrouds that were set over the top of the existing galvavized ductwork. They did this to provide the 'Shading effect' they hoped would drop their electric bill and cool all their labs below. It had next to zero effect as the metal shroud got to 196 degrees and radiated that heat inwards to the galvanized ducts. They had no clue about heat transfer. Ther was a 4 inch distance between the shoud and the duct metal. They still experienced heat gain from radiation and convection.
In the hot months, ANYTHING you can do to provide shade will help.
I'm with you on the small local shading as shown in the study, don't think it makes much difference. Moving the condenser from the sunny to shaded side of the building *may* be different due to the potentially cooler air entering the condenser. Outdoor temp sensors for weather stations show a higher temp on the sunny side of the building even when the sensor is shaded.