How to solve

Either:

legally mandatory $($describes how work must be done to meet NZ laws$)$

voluntary compliance $($describes the industry accepted best practice for employers and employees to comply with NZ laws$).$

AS$/$NZS $3000$: $2007$

Electrical installations $($known as the Australian$/$New Zealand Wiring Rules$)$

legally mandatory

AS$/$NZS $1668\mathrm{.}1$:$1998$

The use of ventilation and airconditioning in buildings $-$ Fire and smoke control in multi$-$compartment buildings

AS$/$NZS $1667\mathrm{.}2$:$1998$

Refrigerating systems $-$ Safety requirements for fixed applications

voluntary compliance

AS$/$NZS $3666\mathrm{.}3$: $2011$

Air$-$handling and water systems of buildings $-$ Microbial control $-$ Part $3$:

voluntary

Performance$-$based maintenance of cooling water systems