Specification 44

What is Specification 44?

Specification 44 provides defined limits for allowable heating load, cooling load, and total thermal energy load (H6P1) based on climate and Class 1 habitable areas. Rather than using a NatHERS star rating, a first-principles Performance Solution directly applies these limits to demonstrate compliance.

The design process begins with a Performance-Based Design Brief that establishes thermal performance criteria referencing Specification 44 limits. Designers then calculate heating, cooling, and combined loads using location-specific climate and area data, in accordance with S44C2–C4. When the design remains within these benchmarks, it satisfies H6P1 requirements.

This approach provides flexibility, particularly for unique or non-standard homes. All designs must be verified by a certifier or authority. While Specification 44 benchmarks derive from previous NatHERS DTS data, they have been generalised for broader application across all climate zones and house sizes.

Relationship Between Specification 44 and NatHERS

Specification 44 and NatHERS serve distinct purposes and employ different methodologies. While they may appear similar, they are not directly comparable.

Specification 44 uses a performance-based approach with specific assumptions, inputs, and calculation methods tailored to demonstrating compliance with building code requirements.

NatHERS functions primarily as a rating tool focused on energy ratings, utilising software accredited under the Nationwide House Energy Rating Scheme.

When modelling the same building, outputs from Specification 44 and NatHERS will differ due to variations in:

• Input data requirements

• Space definitions

• Area calculation methods

• Performance assessment criteria

For example, Specification 44 considers only habitable spaces when determining energy limits, while NatHERS includes all spaces in its thermal performance analysis.

Space Classifications

Habitable Spaces

Habitable spaces are areas used for everyday domestic living. These are the only spaces considered when determining Specification 44 limits and include:

• Bedrooms

• Living rooms

• Dining areas

• Kitchens

• Studies

• Playrooms

• Family rooms

• Home theatres

• Sunrooms

• Similar living spaces

Non-habitable Spaces

Non-habitable spaces are areas not frequently used or occupied for extended periods. These spaces are excluded from Specification 44 limit calculations and include:

• Bathrooms

• Laundries

• Toilets

• Pantries

• Walk-in wardrobes

• Corridors and hallways

• Lobbies

• Darkrooms

• Drying rooms

• Other specialized utility spaces

Our Specification 44 Approach

We provide a Class 1 Performance Solution for National Construction Code requirements through our Specification 44 modelling approach. Our system features an automated 'reference model' generated based on your building's climate zone and house size. This automation significantly reduces time and effort, allowing you to focus on design optimisation.

Our Specification 44 Modelling Process

Our streamlined Specification 44 modelling process enables you to complete a design for a small home (under 350 m²) in approximately one hour. The workflow is designed to guide you efficiently from drawings to results.

1

Create a Project & Design

Initialise your new project and create a design to start building your model.

2

Import Drawings

Upload floor plans for each level of your design.

3

Define Thermal Zones

Trace over the floor plans to define thermal zones with habitable and non-habitable spaces.

4

Specify Wall, Roof, Floor & Glazing Systems

Provide specification for your building envelope.

5

Configure Spaces

Add detailed information for each space:

• Occupant profiles

• Lighting specifications

• Equipment loads

• Infiltration rates

• Ventilation requirements

6

Run Simulation

Execute the performance analysis to generate heating load, cooling load, and total thermal energy load limits and values for your proposed design.

Default Settings and Inputs

When undertaking a first-principles Performance Solution, the following inputs are prioritised:

• Occupant profiles

• Lighting specifications

• Equipment loads

• Infiltration rates

• Ventilation requirements

Default Space Type Classifications

The following space types must be distributed to appropriately represent the Class 1 building:

• Default (Habitable spaces)

• Non-habitable spaces

• Bedrooms (Habitable spaces)

• Kitchen (Habitable spaces)

• Garage (Unconditioned)

Each space type has predefined schedules and internal load profiles based on H6V2 Verification requirements.