Judgeford Homestar Home

The Goal

The owner’s key objective was to design and build a house based on Homestar building principles that would be as warm, sustainable and most energy efficient as possible. The ultimate aim of the design was achieving a rating of 9 or 10 under the Homestar reference framework. To put this into perspective, most new homes built to the Building Code will only achieve a 3-4 Homestar rating scale, and most existing New Zealand dwellings only achieve a 2-3 Homestar rating scale.

To rate a home’s performance and environmental impact, Homestar awards points across seven categories with one being energy. The type of water heating chosen can therefore significantly impact the Homestar rating.

With traditional electric hot water cylinder systems accounting for as much as 27% of a typical power bill*, the family was therefore specifically looking for an alternative hot water heating system that was as energy efficient as possible, with minimal carbon footprint to meet the Homestar rating criteria.

^{*Based on Electrical Authority – Electricity in New Zealand 2018 report.}

The Challenge

Due to the design of the house, the need for heating was minimal however the requirement for hot water remained the same. The family was keen to futureproof and as such, they wanted a super-efficient hot water system that in time could have towel warming radiators or additional space heating added if required. As the house was to be rated under Homestar they also wanted a water heating solution that was as environmentally friendly as possible.

The Solution

The clients specifically chose a next-generation Ecodan QUHZ Hot Water Heat Pump because they wanted a solution with minimal carbon footprint.

The homeowners were acutely aware that traditional electric hot water heaters produce up to three times the amount of greenhouse gas compared to a low emission alternative such as a hot water heat pump. Furthermore, instant gas hot water systems are even greater greenhouse gas contributors producing a staggering seven times more emissions compared to hot water heat pump technology*. As such, it was an easy choice for this family to choose a hot water heat pump over other forms of water heating.

^{*Based on electrical and gas emission factor for New Zealand.}

Super-Efficient Low Carbon Ecodan QUHZ Hot Water Heat Pump

• A 4kW capacity Mitsubishi Electric Ecodan QUHZ Hot Water Heat Pump System was the perfect solution to cover the daily hot water requirements. The system has been specifically designed to operate with exceptionally high efficiency in the production of hot water and is ideal to satisfy the requirements for new build homes and can also be retrofitted in existing homes.
• Super-efficient CO₂ refrigerant is used to heat the domestic hot water which has a Global Warming Potential of 1, making it the number one environmental choice for domestic hot water heating.
• Pre-plumbed and wired, the system is quick and easy to install with only water pipe connections between outdoor unit and cylinder.

Packaged Ecodan 200L Thermal Store Cylinder

• The Ecodan QUHZ provides hot water to the home using a dedicated pre-plumbed 200 litre thermal store. This cylinder is specifically designed to enable efficient production of hot water for a household of up to four people and uses advanced control logic to provide optimum performance at all times.
• This system uses a heat store rather than potable stored water to enable good stratification of the heat store. This maintains the system’s efficiency and allows fresh cold water to be instantly heated up through the integrated heat exchanger, eliminating any potential issues with legionella associated with traditional stored water systems in the tank.

Built-In Smart Control with Energy Monitoring

The integrated controller offers energy monitoring and management of the Ecodan Hot Water Heat Pump System. As a result, the homeowners now have the visibility and freedom to efficiently manage their overall water heating power consumption. Energy monitoring enables the family to take advantage of off-peak tariffs, saving even more on their electricity bill.

The Result

The Ecodan Hot Water Heat Pump System has now seen its first winter and has performed just as expected – using minimal energy possible to generate hot water for the home. This house has achieved the homeowners’ and the designer’s goal of being a low energy, high-performance abode.

This house built to Homestar principles compared to one built to a 4-star standard, has seen significant overall running cost reductions especially in energy and water savings. Over seven years (the expected homeownership period), a house with a Homestar rating of 9 is projected to enjoy annual savings on energy and water bills of over $573-$729 per year*.

^{*NZGBC Website – How Homestar means cheaper bills}