Please click on a link to find out more about our current research programme or download a summary of the overall programme.

Energy
Building Energy End-use Study (BEES)
Performance of cladding systems using solar radiation to pre-heat air
Heat pumps and active cooling in New Zealand homes

Environment
Healthy Housing Index

Structural engineering
Multifunction timber joints

Fire engineering
Managing fire risk in the New Zealand built environment
Quantifying Building Code performance criteria for fire safety
Design fires for apartment buildings

Materials
Understanding of interactions of materials
The role of the underlay in moisture control in roof spaces
Composites

Energy

Building Energy End-use Study (BEES)
Understanding how energy and water resources are used in today's commercial buildings will make it possible to use them more efficiently and so enhance New Zealand's sustainability. An efficiency improvement of 10% would give $90 million fuel and at least $2 million direct GHG savings per year.

From 2008 and in the subsequent five years the Building Energy End-use Study (BEES) will make the first step toward these efficiency improvements by establishing (a) where and how resources are used, and (b) the determinants of resource use.

The overall results of this project will be:

• Quality data on the uses of energy and water in New Zealand commercial buildings
• An improved basis for policy development and implementation, including any future New Zealand Energy Strategy (NZES) and the National Energy Efficiency and Conservation Strategy (NZNEECS)
• Guidance to create more productive work environments
• Support for reduction of GHG (Kyoto) emissions and adaptation to climate change
• Design and operation guidance to reduce greehouse gas emissions
• Improved basis for development of the New Zealand Building Code, Standards, Green Star and design guidance
• Improved models for commercial sector energy (including electricity) use

The BEES research will help understand the relationships between energy and water use in different types of commercial buildings. The results will help provide the opportunities to improve energy and water use efficiency. The scientific design will build on the experiences of the Household Energy End-use Project (HEEP), understanding energy use in residential buildings and members of the team's work in energy studies and audits of commercial buildings.

The data from the monitoring of all fuels (electricity, natural gas, LPG, oil and possibly solid fuel) and water will be combined with end use data (space temperatures, lighting, hot water, appliances, etc) in an integrated database and analysis system. This will contribute towards the development of energy efficiency tools and instruments for commercial buildings and their use, in New Zealand and internationally.

BEES is funded by BRANZ; the Foundation for Reseach, Science and Technology; the Department of Building and housing; and EECA. The work is being carried out by BRANZ; CRESA; the Centre for Building Performance Research at Victoria University of Wellington; and Energy Solutions Ltd.

BEES will form part of IEA SHAC Task 40, Towards Net Zero Energy Solar Buildings.

If you have any more queries regarding this study please email bees@branz.co.nz or call 0800 886 422.

Performance of cladding systems using solar radiation to pre-heat air
Transpired metal membrane collectors have been claimed to be able to provide background ventilation and solar heating of building spaces through a simple low-tech approach that seems applicable to New Zealand's mild sunny climate conditions in many parts of the country, and have been identified in the Zero and Low Energy House project (ZALEH) as one potential energy technology suitable for retrofit installations of existing buildings. One particular application is as a retrofit technology in schools that have been shown in previous BRANZ research to suffer from low air quality and poor thermal performance.

An evaluation of the thermal performance and practical installation and operational issues for this technology was carried out in an actual installation on a house in suburban Wellington.

Further work has now been commissioned to examine its applicability in other climate regions of New Zealand, and in schools.

Heat pumps and active cooling in New Zealand homes
Heat pumps for space conditioning are being adopted widely in New Zealand. An initial study examined this rate of uptake, the possible impact on the electricity supply infrastructure of a widespread shift towards heat pumps for space conditioning, and potential broader impacts of the shift towards heat pumps as a result of the national emphasis on cleaner sources of energy and environmental responsibility.

A broader focus project is now under way which is looking at how 'active' heating and cooling are used in New Zealand homes. This is expected to be complete in 2009.

Environment

Healthy Housing Index
As awareness grows that the house environment is an important factor in health, policy makers are seeing a need for a Healthy Housing Index (HHI) to mirror the Deprivation Index that has been in use in New Zealand for some time. A HHI would provide policy makers with a tool to assess the degree of house-related health issues within any chosen sub-group of houses, allow quantification of the improvement in health likely to result from house retrofits and other interventions, quantify the success of any improvements, allow precise targeting and provide a communication tool between agencies, government and the public. In meetings held by BRANZ with staff from the Wellington School of Medicine and others, wide interest has been shown for this concept by several government departments, including the Ministry of Health, Te Puni Kokiri, Housing New Zealand Corporation, Work and Income New Zealand, the Energy Efficiency and Conservation Authority and the Department of Building and Housing, as well as Wellington City Council and District Health Boards.

More about the Healthy Housing Index.

Structural engineering

Multifunction timber joints
High density urban living is now becoming a popular way of arresting the problem of urban sprawl. To achieve a higher density of population, the most obvious way is to build up rather than out. As a result of this change, multiple storey timber framed apartment buildings are becoming more attractive. The joints between the walls and floors of such buildings have a function of structurally connecting the elements of the building together while, at the same time, fire must be prevented from passing from one occupancy to the other. Also, both airborne and structure-borne sound transmission is to be kept to a level that satisfies the requirements of the NZ Building Code, but to achieve this, structural discontinuity is preferred. This challenging multi-faceted problem is being explored by BRANZ, supplemented by acoustic scientists from Scion and University of Auckland, in a major programme scheduled to run to late 2009.

Fire engineering

Managing fire risk in the New Zealand built environment
Quantitative risk assessment (QRA) is growing in importance both within New Zealand and internationally in fire safety evaluation. While complex risk models have been developed, these are principally research tools that have been used to assess certain Building Code requirements in Canada and Australia. At building project design level, QRA (if used at all) tends to be a somewhat simplified process with a tendency to adopt event-tree methods for the analysis with relatively simple consequence assessments. This may be in terms of the expected number of deaths, or people threatened, or expected property loss.

Recent determinations from the Department of Building and Housing (DBH) have signalled an expectation that a higher standard of analysis is to be applied to alternative solutions that differ significantly from the acceptable solution and that "there is as yet inadequate data for fire engineering to achieve the accuracy that is expected from, for example, structural engineering".

Work has therefore been commissioned to provide designers and regulators with guidance on quantitative risk assessment methodology and provide tools and data for use with those methodologies that are relevant to the New Zealand building stock and design practices. The Canadian-developed FIERAsystem will be used as a basis for a fire risk model that will allow users to simulate industrial building fire outcomes in a probabilistic form and thus provide a measure of the uncertainty in the result, and will build on the current project on fire in industrial buildings co-funded with NZ Fire Service Commission. The project will also integrate previous work by both BRANZ (BRANZFIRE model) and the University of Canterbury (building product model), and the current BRANZ/CSIRO/University of Canterbury project on design fires in apartment buildings into a risk-based assessment model.

Quantifying Building Code performance criteria for fire safety
At present, the mandatory levels of the New Zealand Building Code for fire safety (as for a number of other areas) express required performance using qualitative statements. This leads to inconsistency in interpretations and over-reliance on the subjective judgements of both the designer and approval authorities. There is a trend towards increasing levels of risk aversion by BCAs towards alternative solutions, which will serve to stifle innovation in the industry.

Internationally, there is general consensus that clear quantitative performance criteria are fundamental for a performance-based code. Increasing the amount of quantification in the Code will reduce uncertainty in the building consent process and provide a more transparent process for developing both alternative solutions and acceptable solutions that are technically robust, and provide a better basis for developing higher-level performance criteria.

BRANZ was commissioned to analyse the existing NZBC Approved Solution C/AS1, as a scoping study, to identify any inherent performance levels included or absent. The assumptions and technical basis for different parts of the acceptable solution (where known) will be documented in a summary report, with attention drawn to areas where desirable quantification is missing or where the quantification has an inadequate basis.

Design fires for apartment buildings
The implementation of performance-based fire designs has been restricted by a lack of quantitative performance criteria in the New Zealand Building Code fire safety clauses. This has resulted in considerable subjectivity and inconsistencies for both fire engineering designers and approving authorities. Appropriate design fire scenarios are an example of one of the most important quantitative performance criteria required for performance-based fire designs. Publishing design fire guidelines would be of considerable benefit to the fire engineering community generally by providing a level of design confidence similar to that provided to structural engineers in New Zealand by the Loadings Code. Such a guidance document would deliver economic benefits by providing a sound technical basis to facilitate more extensive implementation of performance-based fire design and would also result in an improved level of fire safety in New Zealand buildings. The research was funded jointly by BRANZ and the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) and is being carried out by BRANZ, CSIRO and the University of Canterbury.

Materials

Understanding of interactions of materials
This major contract to BRANZ Ltd has four key elements:

• Creation of a framework that systemises knowledge regarding the durability of building materials in the New Zealand environment, inclusive of all common building materials used in New Zealand.
• Identification of critical gaps in this framework that need to be addressed by further research and publication of these research needs for industry scrutiny.
• Development of a state-of-the-art Durability Verification Method based on recognised analytical methods and mathematical models plus accelerated laboratory testing (with a focus on using existing information rather than developing new methodologies).
• Development of a web-enabled computerised knowledge system that will manage the complexity of information generated by the project and provide widely-accessible and rapidly-deliverable technology transfer, appropriate to time-stressed industry professionals.

The work is expected to take around three years from 2006 and will involve close collaboration with Standards NZ and the Department of Building and Housing, since the Durability Verification Method has a strong possibility of augmenting or replacing B2/VM1 in future revisions of the NZ Building Code.

The role of the underlay in moisture control in roof spaces
As we have learnt more about control of moisture in walls, we have increasingly realised how little we know about moisture control in roof spaces. In particular, we know little about the role (and so the necessary material properties) of roofing underlays to deliver this control and the effects of more or less ventilation. This research programme by BRANZ Ltd will develop a validated model of the moisture levels attained in roof spaces, and so assist specification of the materials and detailing for use in controlling moisture levels in roof spaces. A further result will be the proposal of a suite of tests that should be applied to underlay materials to assess their fitness for purpose. The work will involve the building and monitoring of specific test structures and, consequently, will take at least two years to complete. Completion is presently planned for late 2009.

Preliminary report:

Composites
The interest in and utilisation of polymer-based composite materials has steadily grown over the last three decades. Their high strength to weight ratio and rot and corrosion resistance has seen them used within an increasing number of diverse applications, from armouring through to yachting and transport. Overseas, composites are also increasingly being used within the building industry, including a number of structural applications and framing. The use of these materials within New Zealand is also on the increase, particularly for claddings, and the polymer-based composites have been used in architectural applications within buildings for a number of years. However, their potential use for numerous other applications within residential and commercial buildings has not yet been fully investigated. The performance and durability issues associated with polymer-based composites have also not been fully investigated for New Zealand conditions. The initial work examined the use, performance and potential of polymer-based composite materials within the building industry.