Integrated HVAC and DHW production systems for Zero Energy Buildings

The integration of different energy sources to cover with the maximum efficiency the building energy demand is one of the principles for achieving the target of the nearly net Zero Energy Buildings (nNZEBs), as defined by the EPBD recast (2010/31/EU). Following this principle, there has been a shift from a conventional mono-carrier/mono-converter based logic (one energy source is used in one energy converter to meet each load) to a multi-carrier/multi-converter logic (a mix of energy sources feeds two or more energy converters to cover the energy loads). This paper reviews the technology, performance and the parameters of the latest multi-energy systems for residential ZEB on the market. The scope of the work is to provide the necessary information in order to design and operate integrated HVAC and domestic hot water (DHW) production systems. After characterising the building energy demand (forms of energy, thermal levels, peak loads and so on), the review focuses on integrated energy systems providing: heating energy for space heating and DHW production; heating and cooling energy for air conditioning and DHW production; heating energy for space heating, DHW production and electricity; heating and cooling energy for air conditioning, DHW production and mechanical ventilation. A schematic of each technology and a table contrasting the strengths, advantages, weaknesses and drawbacks of the various technologies are also provided.