Zero-energy home

The concept of Net Zero Energy Homes (NZEH) is relatively new and involves low energy use for heating, cooling, lighting, equipment, ventilation, domestic hot water, etc, in buildings. It encourages passive strategies such as the use of insulation, day-lighting, natural ventilation, efficient equipment, solar collector, window-to-wall ratio, orientation of building, ground heat exchanger, etc.
After reducing the energy needs of a building through conventional means, the balance of energy is provided by a renewable energy source such as photovoltaic (PV) or wind. As NZEHs are connected to the main grid lines, if they generatesenergy over and above requirement then this extra energy can be exported to the grid, and when there is need, the required energy can be imported back.
Imran Iqbal
Islamabad