Energy

Designing homes to conserve energy and use it efficiently, from sources that cause least environmental harm.

Water heating

According to the BRANZ Household Energy End-Use Project (HEEP), water heating accounts for 29% of energy use in an average New Zealand house.

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Achieving energy-efficient water heating

To achieve energy efficiency in water heating:

  • install efficient hot water outlets that minimise the amount of hot water used
  • use energy-efficient heating sources that do least harm to the environment
  • plan to minimise heat losses from the system.

Minimise heat losses by:

  • heating and storing only as much water as is needed to meet peak demand
  • only heating water to the temperature needed to meet regulatory requirements
  • installing a Grade A insulated cylinder (specifying an additional cylinder wrap will further reduce heat losses)
  • locating the cylinder in a warm space
  • ensuring all hot water pipes are insulated
  • minimising the length of hot water pipes by locating the hot water cylinder central to water heating services
  • incorporating appliances that heat their own water.

Key decisions when specifying water heating systems

Key decisions that have to be made as part of the design process include:

  • locations of water heaters and outlets
  • heating energy source
  • whether to store hot water or use a continuous flow system
  • the capacity of the system.

The choice between a storage or continuous flow system may be influenced by:

  • the energy source readily available
  • space available for installation
  • use patterns and number of occupants within the house
  • distance between the water heater and the point of use within the house.

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