Zenith angle is the angle between vertical line and the line intersecting the sun.

A building with net zero energy consumption, meaning the total amount of energy used by the building on an annual basis is equal to the amount of renewable energy created on the site or in other definitions by renewable energy sources offsite, using technology such as heat pumps, high efficiency windows and insulation, and solar panels.

The zero-energy universe hypothesis proposes that the total amount of energy in the universe is exactly zero: its amount of positive energy in the form of matter is exactly canceled out by its negative energy in the form of gravity.

A building having essentially zero heating demand, defined as having heating demand less than 3 kWh/(m2a).

Zero-point energy is the lowest possible energy that a quantum mechanical system may have.

A zigzag transformer is a special-purpose transformer with a zigzag or "interconnected star" winding connection, it is used as a grounding transformer, creating a missing neutral connection from an ungrounded 3-phase system.

A hard, white metal with a good resistance to atmospheric corrosion. It is used as a coating for steel in a process called galvanizing and also as an alloying element.

Zinc-filled paints based on an inorganic binder. Zinc silicates give very hard films, and are resistant to solvents.

Zinc–air batteries are non-rechargeable metal–air batteries powered by oxidizing zinc with oxygen from the air.

Zinc–air fuel cells are mechanically rechargeable metal–air batteries powered by oxidizing zinc with oxygen from the air.

A dry cell primary battery that provides direct electric current from the electrochemical reaction between zinc and manganese dioxide.

A zone of visual influence is the area from which a development or other structure is theoretically visible. It is usually represented as a map using color to indicate visibility.