Table 5.

Summary of various NZEB approaches

Energy infrastructure connections
NZEB approaches	Technologies	Remarks
Electrical grid	• PV, PV/T, BIPV, solar CHP (i.e. ORC) • Wind turbine • Biomass CHP	• The most widely used, with easy accessibility
District heating	• Solar hot water • Wind heat generator • Biomass boiler, biomass CHP	• Requires district heating networks • Smart thermal grids can accept exported thermal energy
Energy storage	• Electrical energy storage (battery, electric vehicle) • Thermal energy storage (sensible, latent) • Chemical energy storage (hydrogen, hydrogen vehicle, fuel cell vehicle)	• Full energy storage can realize off-grid net-zero goals for remote buildings or facilities • Vehicle battery storage increases local use of renewable energy and reduces energy import/export.
Renewable energy sources
NZEB approaches	Technologies	Remarks
Solar energy	• Solar hot air, solar hot water • PV, PV/T, BIPV, solar CHP	• The efficiency and cost are different for different system • Unit cost relatively independent of installation size
Wind energy	• Wind turbine	• Small-scale wind turbines are generally less cost effective than medium- and large-models • Hybrid PV/wind systems can be used to overcome the dependency on a single renewable source and to avoid the oversizing of renewable components
Biomass energy	• Micro-CHP, including Stirling engine, ORC, internal combustion engine, and fuel cell	• The electrical to thermal ratio and cost differ amongst micro-CHPs • The micro fuel cells are very expensive at present and have a relatively short lifetime
Energy-efficiency measures
NZEB approaches	Technologies	Remarks
Improved building designs	• Increased thermal insulation • Increased thermal capacitance • Higher levels of airtightness • Optimized orientation/shape • Window-to-wall ratio • Window glazing, solar shading • Passive solar technologies, etc.	• Increased insulation and airtightness are effective in heating-dominated buildings but may increase energy use for cooling-dominated buildings
Efficient HVAC systems	• Ventilation (HRV, ERV, natural ventilation, earth-to-air heat exchanger) • Dehumidification (dedicated dehumidification mode of heat pump, desiccant dehumidification) • Heat pump (ASHP, exhaust-air ASHP, low-temperature ASHP, solar-assisted ASHP, GSHP, advanced GHX types)	• HVAC system must be selected to match the local climate
Efficient DHW systems	• Solar water heater • Desuperheater of air-conditioner • Heat pump water heater • Solar-assisted ASHP	• DHW system must be selected to match the local climate
PCM integration	• PCM cold storage • PCM heat storage	• PCM thermal resistance will greatly affect the energy benefit
Miscellaneous	• Smart control • Efficient occupant behavior • Efficient lighting • Efficient appliance	• Some technologies (e.g., efficient lighting, efficient appliance) reduce electricity use directly and also reduce the HVAC load