Air Conditioner Noise | Heat Pump Noise Reduction
Residential air conditioner and heat pump noise has become one of the most common noise complaints, affecting people all over the country.
Higher density building increases these complaints dramatically. Good neighbors can easily develop negative, if not sometimes hostile, attitudes towards each other over the incessant noise. There are many studies which indicate the adverse effects of noise relating to health and social harmony. Having tension between neighbors is not conducive to a good community.
Unfortunately it is quite common to find your neighbor’s air conditioner/heat pump is directly opposite your bedroom window, or vice versa. Many times the developer has given little consideration to the placement or, there just was no other place to position it.
Foliage or landscaping is ineffective as a method to reduce this type of noise, or any other for that matter. Trees can actually aggravate the situation as sound reflects in all directions from the leaves and branches.
1. There is no such thing as complete soundproofing even using our All Weather Sound Panels.
2. A simple way to understand the acoustics of your sound problem from the unit is to consider your unit as a very bright light bulb on a very dark night. You may be able to fence it in with something solid, perhaps four or five feet up. Now imagine that you are standing at your neighbor’s window (or complaint area). Will you still see any light? Indeed you will! You will see the light reflected off virtually every surface other than the solid barrier placed between yourself and the light. Sound acts in exactly the same manner, reflecting off all hard surfaces in all directions. Therefore, the barriers to be placed around the heat pump must not only be good at blocking sound but also extremely good at not reflecting it out of the boxed-in area.
3. You must consider every surface around the unit that reflects sound. The reflectivity of the surface or material is measure by its “noise reduction coefficient” (NRC). An NRC of 1.00 is the highest level of non-reflectivity. Numbers below 1.00 increase in reflectivity the lower the number. A concrete wall for example has an NRC of 0.05, painted brick, 0.00 or extremely low absorption. Most residential exterior walls are usually one to two feet away from the unit and as such, they reflect virtually all sound back in all directions. Covering the wall next to the heat pump with a highly sound absorbent material is essential. The more area covered, the better, and the higher the NRC, the better.
4. Optimum performance in reducing heat pump noise would be using a high STC (sound transmission classification, the higher the number, the better) “barrier” which has the highest possible NRC to reduce all reflections of the boxed-in area. Keep in mind that an adequate amount of airflow must be maintained for the unit to function properly.
5. Typical PVC or wooden fences do very little to reduce the noise as they are poor “barriers” (low STC) and have virtually no “acoustical absorbency” (NRC). They are also difficult to remove for servicing of the unit.
6. Sound can be extremely complex and does not always act in the way one would expect. To really understand what will happen acoustically when using various barriers or acoustically absorbent materials only independent laboratory tests or advanced acoustical prediction software analysis should be relied upon for accuracy.