Sustainable Design Tools

We provide the service of Homestar Design / Assessment or Passive House Certification and can either utilize the tools for your project or take you all the way through the process to gain a Homestar Rating or a Certified Passive House. We are also experienced with utilizing the Earth Building Standards and Alternative solutions required for using natural materials in you building, such as strawbale and natural plasters among others. We have outlined more information below.


​Homestar Design

Energy Modelling / Homestar Assessment
Homestar is an independent rating tool for assessing the health, efficiency, and sustainability of homes across New Zealand and is increasingly being recognized as adding value to your project.
There are three key parts to Homestar assessments:
  • Energy Modelling, using ECCHO, a simplified version of Passive House software.
  • Embodied Carbon Calculation, using an excel spreadsheet software.
  • Sustainable healthy materials, Water conservation, natural lighting assessment.
All of these are required to achieve Homestar certification.
Elizabeth has undergone training to be a Homestar Designer and Assessor, and we can now provide the full Homestar rating package or any one part of it. ​


Benefits of Homestar
  • Ensure your home is built well above the NZ Building Code (the NZBC is a minimum standard of performance and is at a level well below accepted overseas standards).
  • Create a high-performance, healthy home which also provides annual energy and water cost savings. (Annual operational cost savings from a Homestar rated home average between $450 to $500 per annum and more for a passive house).
  • With full Homestar certification you can obtain mortgage interest rate benefits by applying for ANZs healthy home loan. (Interest rate discounts currently from 0.7 % p.a.  to 1%p.a.)
  • Assess cost-benefit versus performance so that the selection of systems, components and materials within your home aligns building performance and your budget.
  • Know how much embodied energy is in your building and get real about climate change action by implementing design modifications to reduce carbon emissions.
  • Add long-term value within a property market growing increasingly aware of the benefits of building performance.
Process
To ensure optimal building performance is obtained the factors associated with the three key parts of the Homestar Assessment are considered from concept through detailed design and include assessments of the building as-built on site. Baseline modelling is revised to suit construction detailing and material selection as the design progresses.
 
Energy modelling
Energy modelling analyzes your home from a design perspective (window openings, orientation, and shading) as well as from a componentry perspective (thermal performance of floors, walls, roofs, and windows, airtightness etc.).
Different options for building components can be inputted to test different construction and systems scenarios.  If a cost estimate has been prepared by a Quantity Surveyor we can undertake a detailed cost-benefit versus performance assessment so that the selection of systems, components and materials aligns your building’s performance and your budget.
This assessment quantifies the present value cost comparisons of upfront investment versus the cost savings over the building’s lifetime. Experience from other buildings shows that the cost savings between an energy efficient building and a non-energy efficient building can be in the tens of thousands of dollars over a 50-year period. However, without doing the calculations, we can only estimate the benefits of certain design decisions.
Given these benefits, we still recommend undertaking energy modelling of your proposed design, even if you are not planning on obtaining full Homestar certification, as this enables us to ensure your building performance is optimized in line with your budget to create a healthy home, with the benefit of annual operational savings.

If you would like us to provide this service or any part of it in addition to the normal design work, please let us know. 

Passive House Design and Certification

 We are able to provide services in passive house design consultation, and we recommend taking your project all the way through to a certified passive house. Elizabeth is our certified Passive House Designer on the team. ​
A passive house addresses all the problems you have heard of with common New Zealand homes (cold, moldy, drafty). 
A passive house has a stable temperature all year round, with minimal electrical input. In fact, the main part of the electrical bill is from hot water heating for bathing. 

By using the PHPP Software, the passive house designer can figure out the square meter kWh use of energy per annum for heating and cooling. In order to pass certification, it needs to be below 15 kWh/ m2 / annum. There are a few other criteria which our team can go through with you. The software incorporate very site specific information. We are able to calculate the annual energy costs with or without utilizing passive house design changes for the same shape / size house, and show to you the cost benefits in the long term of some higher upfront costs of more insulation and airtight membranes, better quality windows, and a Heat Recovery Ventilation system. 

In order to achieve a passive house, the walls, roofs, floors, and windows have a higher insulation value than normal. The lower South Island is considered a Cool Temperate Climate, and mid to higher South Island is a Warm Temperate climate. 

For Southland and Otago (Cool Temperate Climate), We would be looking at achieving the following R values generally: 
Floors: R 5.5
Walls: R 7.14
Roofs: R 10

For other parts of the South Island more towards Nelson (Warm temperate Climate) generally: 
Floors: R 2.2
Walls: R 3.3
Roofs: R 5.5

The new H1 Standards for the building code are now requiring buildings to reach higher R values, closer to those seen in a warm temperate climate. Nevertheless, the building code alone is not dealing with moisture issues. Passive house looks at a house through the lenses of building science, and addresses how to have a warm airtight house, while keeping humidity levels down, and eliminating any detrimental thermal bridges (cold spots in corners of the room where mold can grow). 

Windows are typically triple glazed and shown in U- values. Triple glazed windows come in timber, uPVC and Weathershield provide an aluminum window with a uPVC core. Increasing the thermal quality of the windows is always the first step to reducing heat loss in a building. 

Earth Building Association of NZ

Design & Make Architects staff are active members of the Earth Building Association of NZ. The association is leading the Earth building Standards in New Zealand, and in 2020 updated the standards to include information on Straw Bale Buildings. We encourage clients interested in Natural Building to become a member of this organization and attend their annual conference, which has a wide range of people, and is in a different part of New Zealand each year. There are tours of natural buildings; only by experiencing one can you feel the real joy of natural plasters and earthen floors. 
Delia and Elizabeth have been actively sharing knowledge about natural building techniques and the Earth Building Standards through introduction workshops with a variety of age groups and professionals. Workshops included theory and hands on for builders, designers and Architects in November 2021 as part of the Better Building Workshop in Wanaka. And more recently with a series of workshops including a full day emersion with BCITO apprentices in Cromwell, May 2023.
A follow up Zoom workshop with Architects went into further detail of how to design with the Earth Building Standards, and demonstrated two Strawbale house designs with an Alternative Solution. Design & Make would like to offer more opportunities like this in the Industry to broaden the use of natural materials. 

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