J1V5 Verification using a reference building for a Class 2 sole-occupancy unit

What is J1V5?

Introduced in NCC 2022 - Vol 1, J1V5 is a Verification Method for Class 2 (sole-occupancy unit (SOU)) buildings. Its intent is to provide a modelling pathway to assess multiple performance requirements, similar to a J1V3 workflow. It is intended to be an alternative to NatHERS modelling by meeting strict modelling requirements within Specification 33 and 45.

J1V5 Modelling on Speckel

Our J1V5 modelling approach is unique, where the reference building model (including J1P2 and J1P3) are automated. This approach saves significant time and effort, enabling design optimisation to be the focal point. A typical building is modelled in a few hours, including simulations and results.

The J1V5 Method

The intent of J1V5 is to allow a single energy model to cover all SOUs in an apartment building. This is achieved using a computer simulation tool that is not a NatHERS software tool. J1V5 VURB is a comparative method that assesses the heating and/or cooling load of a theoretical reference SOU and compares it to that of a proposed SOU.

It also compares the energy value of a proposed SOU's domestic services to the benchmark set for a reference SOU. The reference SOU's characteristics are based on certain elemental DTS Provisions in Volume One.

The J1V5 compliance pathway for SOUs in an apartment building is similar to J1V3 but has a key difference: J1V5 allows the energy model to demonstrate the benefits of natural ventilation in maintaining comfort within the apartment.

The J1V5 Requirements

Compliance with J1V5 is provided by two Performance Requirements - J1P2 and J1P3.

J1P2 Requirements

Compliance with J1P2 is verified when each Class 2 sole-occupancy unit of a proposed building meets specific heating and cooling load requirements.

In climate zones 3, 4, 5, 6, 7, and 8, the unit's heating load must not exceed the heating load of a reference building and must be within 120% of the value specified in J1P2(1).

Similarly, in climate zones 1, 2, 3, 4, and 5, the unit's cooling load must not exceed the cooling load of a reference building and must be within 120% of the value specified in J1P2(2).

Additionally, the unit must comply with the relevant requirements outlined in Specifications 33 and 45.

J1P3 Requirements

Compliance with J1P3 is determined when the energy value of the domestic services, including all centralised domestic services infrastructure, of a proposed building is less than that of a reference building.

Each sole-occupancy unit in the reference building must have a 3-star ducted air-to-air heat pump (rated under the 2019 GEMS determination) for heating all heated spaces, a 3-star ducted heat pump (rated under the 2019 GEMS determination) for cooling all cooled spaces, a 5-star instantaneous gas water heater (rated under the 2017 GEMS determination) for providing all domestic heated water, and a lighting power density of 4 W/m² for all internal spaces with artificial lighting.

Additionally, both the proposed building and the reference building must comply with the relevant requirements outlined in Specifications 33 and 45.