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Warmer, drier and healthier buildings

The Warmer, drier and healthier buildings programme is improving our understanding of the issues, exploring solutions and looking at ways of implementing our research findings through evidence-based information.

The Warmer, drier and healthier buildings research programme builds on the WAVE (Weathertightness, Air quality and Ventilation Engineering) programme, which was a 6-year initiative that ended in October 2015. WAVE removed some of the guesswork around moisture and contaminant control in the New Zealand building stock. BRANZ is helping to avoid future issues resulting from changes to materials, designs and construction methods through further research that builds on the WAVE findings.

Programme aims

Our building stock has had a rudimentary approach to the control of heat, air and moisture, and we need to aim for more from our buildings. A multitude of factors, including modern lifestyles, new construction trends and climate change mean that the old rudimentary approach is no longer sufficient. Science needs to be put in place to inform industry how to move from rudimentary to exemplary.

The work under this programme combines to focus on the provision of solutions that will allow buildings to be warm, dry and healthy over their lifetime. It will also provide the information we need to improve comfort, temperature and heating to support better health outcomes.

These are some of the critical success criteria for this programme:

  • Understanding the issues: There is a shared understanding of the issues that prevent our current homes and buildings being warm, dry and healthy.
  • Identifying solutions: Solutions to developing warmer, drier, healthier homes and buildings in New Zealand are successfully identified.
  • Industry understanding: Industry understands the knowledge, ways of implementing the solutions and the benefits provided.
  • Warm, dry, healthy environments: Owners, suppliers and users of homes and buildings have the knowledge and understanding to make effective decisions in producing and maintaining warm, dry, healthy environments.

Research under this programme

Identifying solutions

Airtightness trends, impacts and energy-saving opportunities: This project will expand the current data on airtightness to include homes built since 2010 by using blower door tests on newer properties to test their airtightness. The results will be used to create a national database that can be used to develop ways of mapping, simulating and improving building performance. The project will also carry out tests on older houses to find out the best way of preventing heat loss and improving energy efficiency.

Monitoring conditions and airflows in roofs: At present, we have little information about the ventilation rate and moisture levels in gable and skillion-type roofs. This applies to both residential and commercial roofs. This project will develop methodologies to assess roof performance and provide data to help us understand the physical process behind roof cavity issues. In the long term, the project may lead to a roof airtightness database similar to the house airtightness database. This data will then be able to be applied to help optimise design approaches for roofs.

Roof design pathways: This project will develop a tool to provide guidance to designers and architects on how to design roofs that are properly ventilated whatever the location, climate, design and internal conditions. The project will also help us understand why some roofs fail and provide the industry with strategies they can use to avoid failure.

Testing in the field - expanding BRANZ's experimental building programme: This project will expand BRANZ's experimental building programme by building identical test huts in Central Otago, Christchurch, Auckland and Wellington. These huts will be used for long-term experiments on building elements. They will initially be used to look at the issues that arise when using absorbent claddings over a cavity. This initial project will provide information about the long-term performance of a range of different cavity configurations, surface coatings, insulation and internal wall linings.

Getting homes dry: The purpose of this project is to find out the typical range of humidity levels in New Zealand homes. It will identify where poor operation of the house may be causing high humidity levels and whether those houses form a distinct group.

The potential impact of energy-saving building design on occupant health: Residential building design is evolving to reduce energy demands, carbon dioxide emissions and heating costs to occupants. However, as buildings become more airtight, there can be a general deterioration of indoor air quality. If indoor air quality is compromised by certain design initiatives in terms of chemical contaminants, it is likely that biocontaminants may also thrive in this environment. The outcomes of this research will be to provide guidance on ventilation in the home environment. It will identify the sources and concentration of harmful substances.

Identifying the sources and characteristics of particulates and volatile organic compounds in New Zealand residential dwellings: Volatile organic compounds (VOCs) are known to cause poor air quality. However there has been little research carried out on the sources, compositions and concentrations found in homes in New Zealand. VOCs emitted from housing materials vary greatly in both number and concentrations. They can be found in numerous building materials including glues, paints and varnishes, epoxies, fillers, carpets, veneers and woods. This project will use a dynamic chamber system to capture and identify the compounds and origins of some of the more invasive VOC substances. Dynamic chamber studies have the advantage of providing both emission composition and emission rates under determined environmental conditions. Where possible, means of VOC reduction and /or mitigation will be identified and evaluated. The ultimate project deliverable will be a database identifying materials and associated VOCs and their health effects.

Keeping our children warm and dry - evidence from Growing Up in New Zealand: Growing Up in New Zealand is a flagship New Zealand longitudinal research resource. It consists of data collected about child health and wellbeing, psychosocial and cognitive development, education, family and whānau, culture and identity, and societal context. This project, now completed, piloted an indoor indoor climate measurement protocol within the Growing Up in New Zealand Leading Light children's schools and homes.

This provided valuable insight and understanding of the determinants of poor indoor climate and the health and education outcomes associated with indoor climate. The project supported the development and testing of a process for measuring indoor climate in classrooms and homes. It developed a protocol to utilise simple monitors to make individual-level measurements of temperature, humidity and carbon dioxide in each cohort child's classroom and home.

The advantage of adding this measurement onto an existing cohort study is that these measures will be linked to previously collected information about the family, home and school environments. It also links to individual detailed descriptions of each child's health and development (collected via self-report and via abstraction of data from routinely collected records of primary care visits and hospital admissions). This provides unique insight around the impact of the indoor climates of our schools and homes on New Zealand's children.

For more information see the study report ER58 Keeping our children warm and dry: Evidence from Growing Up in New Zealand (May 2021) and the fact sheet Indoor air quality #7: Keeping our children warm and dry (June 2021)

Industry understanding

Ventilation performance in large-span roofs: Long-run skillion-type roofs are becoming more common in schools and other institutions. However, there are concerns that they do not allow moisture to be removed effectively because of high airflow resistance. This project will provide recommendations and solutions about free air-gap height and whether any additional ventilation openings are required.

Ridge and fascia vent design and performance: Using an experimental rig, this project will establish whether and how water can enter the roof via ventilation openings. It will use wind pressure and rain simulation for outside water. It will use a simulated condensate on the inside of vents for the internal moisture source. The vent designs will be varied to establish best designs by looking at options such as thermally isolated baffles and vent shape for condensate run-off. The project will assess whether there is an issue. If this proves to be the case, it will provide design and/or installation guidelines for fascia and ridge vents to prevent water intrusion into roofs through vents.

Warm, dry, healthy environments

Roof design: Roof design can be complicated. It must balance structural requirements with the demands of the environment and the climate, weathertightness, the ideal slope and aesthetic considerations. Drawing on insight and evidence from other research in this programme, this project will involve producing a series of fact sheets about roof design and cladding. These will be followed by a more comprehensive resource that will provide independent and impartial advice about all roofing types.

More information

To find out more about the Warmer, drier and healthier buildings programme, please contact the Programme Leader Mark Jones.

Explore the range of resources related to the programme.