What windows and doors should I use for H1 compliance?

H1 regulations are part of the New Zealand building code, specifically relating to the energy efficiency and thermal performance of your home. The new H1 requirements were first announced in November 2021 and featured a phased introduction to enable the industry to accommodate the new legislation. As of November 2023, the full requirements were put in place, with all residential housing required to meet the new standards.

But what do the H1 regulations mean, why do these changes matter, and how do you ensure you select the right windows and door configurations that meet compliance, while enhancing your home's aesthetic appeal and practicality? In this article, we will provide you with information to make informed decisions aligned with both the H1 regulations, compliance, and your specific project requirements.

If you're building or renovating you should familiarise yourself with this information, as it can affect your home's overall comfort, energy costs, and compliance. First, we’ll explore the general requirements.

H1 changes and R-value climate zones for windows and doors

The requirements for windows and doors are different from the requirements for roofs, floors, walls, and skylights. While windows and doors have 6 climate zones, walls and roofs have 2, and floors and skylights only have 1. This adds to the complexity and the need for both homeowners and architects to be clear on the geo-specific requirements for the residential home.

And while the guidelines are easy to follow for a new build the changes also impact alterations to an existing building. When assessing the necessary thermal resistance for repaired or replaced building elements. It is essential to take into account the existing performance of the building, the extent of the element being replaced, and the element's contribution to the building's overall performance. In doing so, you can exercise your judgment to ensure that the replacement performs to at least the same standard as the elements fitted previously. The degree to which the building envelope is altered or replaced will determine how closely the repair or replacement should align with the R-values specified for new buildings in the acceptable solutions.

R-values measure the thermal resistance of building materials, and different climate zones in New Zealand require specific R-values for windows, doors, and other elements so that they meet H1 standards. You can achieve the required thermal performance for your home by selecting materials with the appropriate R-values. However, the higher the R-value, the better the insulation, which results in optimal energy efficiency and comfort in your home.

Source: https://www.building.govt.nz

The methods of calculating H1 regulations and compliance

Schedule method

The schedule method is the simplest method of compliance as part of the new H1/AS1 Acceptable Solution for all housing and other buildings under 300m2. Compliance can be achieved by ensuring all building elements in a residential property, like walls, windows, and doors meet or exceed a fixed set of R-values listed in a predefined schedule. However, the schedule method can only be used if the windows are less than 30% of the total wall area. 

It's straightforward, but may not be the most cost-effective option with the increase in R-values that were implemented for roofs, flooring, and windows. 

Calculation method

The calculation method allows for flexibility by balancing different R-values across the property, so long as the overall building performance meets a weighted average insulation value. This enables custom material choices to optimise cost and performance. However, it does require more detailed calculations compared to the schedule method. There are a number of free tools online or available to download that make these calculations easy, here are a couple listed below:

• H1 Calculation Method Calculator
• Energy Efficiency Calculation Method Tool

ModelLing method 

The modelling method is the most detailed approach involving custom modelling of the building’s thermal performance, and usually requiring engineering input. For additional guidance and to ensure your project meets compliance standards, check out the H1 building code compliance tools.

How can DuCo support you with the calculation method?

To simplify this process, we provide tailored advice and support by offering individual or house lot averages of the R-value for your window joinery. This service allows you to utilise the calculation method and change the various building element’s individual R-value ratings so that you meet compliance with more flexibility in the material choices for your home.  

The advantage of increasing your window performance 

Deciding to spend a little more on your windows and doors will ensure your home’s overall energy efficiency meets compliance with the H1 regulations of the building code. 

Windows are generally the lowest-performing thermal efficient element of your home, so increasing your window performance could significantly improve the average performance of your home and contribute to the following:

Energy efficiency

Windows are often the weakest point in a home’s thermal barrier. Preparing to include options like high-performance Low E glass and thermally broken frames can reduce heat loss, increase insulation, and reduce energy bills resulting in all-year-round comfort.

Long-term savings

Spending more on a high-performance window and its features might cost more upfront, but it can reduce the need for extra insulation costs in other parts of your home. This can make compliance more cost-effective, with the use of the calculation method.

Comfort and health

Windows and doors reduce heat loss, maintaining the temperatures of your home and eliminating cold drafts. This increases the overall comfort of your home, contributing to your happiness, health, and well-being, and resulting in a healthy living environment by reducing condensation and preventing mould growth.

Window and door configuration and product considerations 

What should you consider when selecting window and door configurations or features? Some options that can make a significant difference in enhancing overall performance and gain compliance include the following:

Large fixed glass panes

Windows that include large fixed glass panes are often used in modern architectural designs and are designed to ensure you have an unobstructed view while maximising natural light. Fixed glass panes with Low E also have better insulation properties than aluminium frames, which offer higher thermal performance, resulting in being the perfect option for framing views without compromising on energy efficiency. 

Minimal mullions and transoms

Reducing the number of mullions and transoms can minimise thermal bridging, and can lead to optimal energy efficiency. Mullions and transoms are architectural elements that have been specifically designed to support and divide the glass panels of a window or door. While thermally broken frames reduce the thermal bridging it is still present, so the less aluminium included in the frames the higher performance rating you will achieve. 

Large panel sliding and stacker doors

Door configurations like panel sliding and stackers can create fewer interruptions in the thermal envelope. Large panel sliding doors and stacker doors have the ability to maintain views and provide easy access between indoor and outdoor spaces, without compromising on energy efficiency. Using large fixed glass panes these doors have a better thermal performance than a hinged or bifold door.

Additional high-performing products 

Additional features that result in the perfect blend of energy efficiency to reduce the environmental footprint of your home include the following: Solux Ultra glass - a high-performance Low E product that works to particularly minimise overheating, Metro Centra-Fix Suite glass for recessed install frames, and Klima uPVC frames, optimised for New Zealand climate conditions with exceptional durability.

Ensuring compliance and increasing overall performance

We understand there is a comprehensive list of regulations to adhere to when ensuring compliance with the building code, and the energy efficiency of your home. But there are great products and solutions to optimise your windows and doors, to increase the overall energy efficiency of your home while adhering to the H1 building code. At DuCo, we can support you in finding the right balance between energy savings, cost, and design, so we create a space you love to be in. 

If you want to know more about how we can help, contact us today.