Although a clear distinction between mechanical, plumbing and electrical systems can be made, it may be difficult to separate these systems in modern housing where they are all integrated using advanced technologies.  Mechanical systems include space heating, cooling and ventilation systems that are required to control indoor temperatures satisfying comfort living requirements throughout the year.  Design and implementation of ventilation systems consider the adequate delivery of ample fresh air needed for occupant health and safety.  Plumbing and electrical systems are among the most important elements for occupant convenience and are responsible for the safe and reliable distribution of water and electricity.