Design for energy efficiency

Whether you’re planning a new build or renovating your existing home, this page offers practical tips and resources to help you make smart design choices. 

Energy efficient home design 

Design your home to efficiently regulate temperature using well planned window placement, home architecture and materials that hold heat well — for a more comfortable home, year-round.  

Build beyond the building code 

Building a Homestar rated home puts energy efficiency at the heart of your home design. Homestar rated homes use less power through smart design choices like better insulation, ventilation, and shading. These features help prevent dampness, mould, and overheating—common problems in standard builds. 

To receive a Homestar rating, a house must meet additional performance and sustainability requirements above and beyond the New Zealand Building Code. 

Learn more about Homestar(external link)

Energy modelling for new builds 

If you are building new or undertaking any major renovation work involving your walls or windows, it’s recommended to utilise an energy model, such as the ECCHO tool developed by the New Zealand Green Building Council. Energy modelling predicts the way that your new (or existing) home will use energy based on its design, construction and features.  

The modelling results help to guide decisions on insulation, glazing, orientation, and home ventilation systems to optimise energy performance and efficiency, comfort and return on investment.  

Find out more about energy modelling(external link)

Orient your home with sunlight in mind 

Whether you’re building new or already own your home, you can design in extra ways to make the most out of the sun’s natural warmth.  

• Orient your main living areas to face north so they get the most sun. Put service areas like the bathroom, toilet and garage on the cooler south-facing side. 
• Well-designed roof overhangs allow direct sunlight to flood in over winter but provide shade in summer. They work best over north-facing windows. On east or west sides, where the sun is lower, deciduous trees and extendable shades or louvres work better. 

Use heat-absorbing materials 

Solid materials like concrete slabs that absorb and store heat during the day and release it when the temperature drops at night are known as ‘thermal mass’.  

When floors or walls with high thermal mass are placed in rooms that get plenty of sun, they slow the rate of cooling in the evenings and overnight, reducing your need for heating. For example, an insulated concrete floor slab can be included in the design as a passive heating feature – to make the most of it, consider leaving sunlit areas uncovered or finished with tiles, paint, or polished concrete rather than carpet, so the heat can be effectively absorbed and released. Darker finishes tend to increase this heating effect as they absorb more energy from sunlight. 

 
Choose the right windows, and place them wisely 

Windows let heat in but also release heat to colder outside air. Choose larger windows for the sunny north side, smaller on the east and west sides, and smallest on the south side. Place windows so air can flow through rooms for summer cooling. 

Choose double-glazed panes and 'low E' glass (which has an invisible coating that lets in light while trapping heat). These can be retrofitted into older homes or installed when windows need replacing.  

Learn more about window insulation 

Big ticket energy efficiency upgrades 

If you’re thinking about making some big-ticket improvements to improve the energy performance of your home – it pays to think about what your biggest energy users are, and where you’ll get the best return on your investment.   

Rooftop solar 

Households that consume more electricity, particularly in the morning and daytime, see the best financial returns from solar PV. It provides the best value when it’s north facing and on a tilt of 30-45 degrees, and unshaded.  

Given the right circumstances, solar panels can pay themselves off in around 8 years, then deliver low-cost energy for the next 20.  

Find out how much solar could save you 

Ventilation systems 

All homes need ventilation to remove excess moisture and avoid damp and mould.  

The Building Code requires extractor fans in kitchens and bathrooms, but for an energy efficiency boost look at a heat recovery ventilation system.  

This pre-heats air coming into the house by capturing heat from air leaving the house.  

Learn more about ventilation systems