With improved insulation and heating, static electricity may be more noticeable. There are many variables such as the physiological makeup of an individual, weight, walking habits and even the type of shoe soles worn. Static electricity is affected by the face fiber of the carpet, construction of the carpet, the backing, type of cushion under the carpet and the kind of floor. Static electricity may be noticeable and then it will disappear. It may or may not return. The reason it disappeared is the change of some variable. If the carpet is soiled, there will be less static electricity than on a clean carpet. Humidity is probably the biggest factor that produces the change. Moisture in the air will be absorbed by the carpet fibers. The moisture in the fibers is important as the moisture will help to dissipate the electrical charge. If there is sufficient moisture present there will not be enough charge built up to produce a shock. You can create moisture in the air by using a humidifier. You can reduce static electricity by also spraying the carpet with a antistatic agent.