A natural gas regulator reduces gas pressure via a spring valve that pushes against opposing pressure, allowing the valve to open only enough to pressurize the gas within a structure. The regulator regulates gas pressure via a diaphragm attached to the spring valve that reacts to pressure changes.
Homes require natural gas regulators because natural gas is often piped at pressures exceeding the need of residential structures. In addition, gas pressure in outside lines fluctuates. Gas usage within the home also creates pressure changes that the natural gas regulator responds to by allowing more or less gas into the home. Most residential natural gas regulators require no outside energy to operate.