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.

Specification 44 FAQ's

What is the 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.

Note: Comparing results between these two systems is not meaningful. They are independent processes with distinct objectives, and no alignment between their outputs is expected or required.

How do I select my climate zone when modelling a design?

Your climate zone is selected when you create a project alongside the location of your project. The coordinates allow Better Building to identify the nearest climate file and set that as a default for your project.

How does the Lite plan limit modelling in Specification 44?

The Lite plan is set up as a low-cost option for single users and does not limit the number of simulations that can be undertaken for Specification 44. However, it does limit the reports that can be issued from the specification 44 workflow where credits are required. A report costs $25 or 50 Credits. You can extract information from the platform to avoid this cost if you wish to author your own reports.

Can I import DWG files or PDF files for drawing?

Better Building accepts underlays in the form of .png files only. You need to convert PDF or DWG files to .png before uploading. PNG files are used because they are lightweight and improve your experience on the platform.

Does Better Building meet all the requirements of H6P1 Thermal Performance?

Yes. The limits set by Specification 44 as referenced in H6P1 Thermal Performance must all be individually met for compliance. The heating load limit, cooling load limit, and thermal energy load limit are all automatically created for you, and your design needs to ensure your loads are below the limits set by Specification 44.

Can I use my own determined load limits as opposed to automated limits?

Yes. Custom values can be nominated to override the heating, cooling, and dehumidification gram hours to set the load limits. These are provided for those who prefer to use the nominated values in the National Construction Code as opposed to values created from the weather file. We recommend using the weather file for more accurate representation.

How long does it take to undertake a Specification 44 model?

To model a single storey building likely takes only 30 minutes and potentially another 15 minutes for a second storey. This likely represents approximately 70% of the total time required to start assessing your design against Specification 44 heating, cooling, and thermal energy load limits.

What default occupants lighting and equipment loads and densities are assumed within the Specification 44 default setup?

Better Building uses the H6V2 references for occupancy, lights, equipment, and their schedules to provide an initial backstop for all models. Where these densities and schedules are deemed non-applicable to a design, they can be overridden, and alternative appliances can be considered.

What infiltration settings are assumed across the model?

Two default settings are nominated: a 0.35 air change rate for all habitable and non-habitable spaces, and a 0.75 air change rate for the garage space. These values are deemed representative of industry averages and can be changed for all spaces in the model.

How do you account for window openings in the model?

Window openings are accounted for at each window where the openability can be specified within a range of 1 through to 90. They are further optimised under spaces where the temperature difference between inside and outside and the minimum/maximum outdoor temperatures are set. The defaults reflect an adjustment from the set points with a buffer of 0.5 degrees Celsius above and below the set point for window ventilation.

What are Specification 44 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

Can air flow network settings be used in Specification 44?

As of August 2025, adequate testing has not been undertaken to determine the efficacy of air flow networks in Specification 44. While theoretically possible to apply airflow network settings (an advanced calculation method beyond simple window ventilation), they won't be available until later in the year.

Where do the thermostat settings come from for heating and cooling set points?

Thermostat settings are all sourced from H6V2 references for the habitable spaces, kitchen, and bedroom spaces. Refer to the National Construction Code for further information.

Can set points for heating and cooling be changed in the model?

Yes. If you disagree with the set points within the model, they can be changed. For example, if you have a cooling set point and want to reflect ceiling fans, you could feasibly increase the cooling set point by 0.5 or 1 degree to offset the cooling demand.

What are lighting fractions?

Lighting fractions provide a breakdown of visible and radiant fractions and return air fractions. These can be adopted for LED and CFL lighting. Most dwellings will adopt an LED lighting fraction mix, typically represented by 0.52 for visible fraction, 0.33 for radiant fraction, and zero for return air fraction.

What are activity levels, air velocity, clothing insulation method and clothing when fixed, referring to in the occupants tab?

For Specification 44, only the activity level and the schedule and density of the occupant is applicable. Air velocity, clothing insulation method, and clothing (when fixed) can be ignored as they are not applicable to the calculations.

How do I determine the occupancy and cooking load for the space?

On the occupants tab, there's a form that references Table H6V2B for occupancy and cooking equipment loads. You can nominate your floor area of habitable rooms to address the occupancy per meter square per person and the cooking equipment watts per meter squared. These can then be transferred into your model.

For walls, roofs and floors, is thermal bridging required to be assessed?

While not specified, it is believed to be mandatory to account for thermal bridging to get a closer thermal representation of your design for walls, roofs, and floors.

How do I change my floor system if it is not in contact with ground?

Under envelope > floors, you can address your exposure by nominating either ground contact (equivalent to slab on ground), external (could be a suspended floor), or adiabatic floor exposure (no heat transfer). For ground contact, you'll need to toggle "show advanced" to set the density and heat capacity of a slab on ground if applicable.

For windows, are the inputs System U-values or simply glazing U-values?

All inputs pertaining to windows are assumed to be the System U value, including frame, edge, and glass. You can nominate these values if you are an energy rater with experience in this space. These are directly equivalent to the input requirements, with the additional option of adding the openability for each window when specifying thermal performance.

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

We default to H6V2 Verification using reference building sections O-F to establish schedules and internal loads for different space types. These can be updated, as required.

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.