October 31, 2024
Project Management

Planning considerations for high-energy efficiency building projects

Max Mayer

To achieve a building design which accomplishes high-energy efficiency with a low-carbon footprint and low ongoing costs, there are key elements to consider.

In this article, Max Mayer, Senior Project Manager at WT, details the building considerations all stakeholders should address when undertaking high-energy efficiency projects.

Regulating bodies encourage the Passivhaus standard, a tried and tested quality assurance standard for energy efficient buildings. Additionally, planning projects to meet certification requirements like Homestar and Greenstar, as well as H1 compliance, involves rigorous building considerations.

Max Mayer, Senior Project Manager at WT, details the building considerations all stakeholders should address when undertaking high-energy efficiency projects. These can be categorised into layout, envelope, and plant elements, and used as a guide.

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Building layout considerations	Considered?
Building orientation relative to the sun's path affects energy consumption. Less sun exposure reduces cooling needs, which requires energy to operate.	☐
Optimal roof design, like large low-pitch or inverted (butterfly) roofs, suits solar PV for cost-effective energy offset.	☐
Natural light provision, in order to reduce artificial lighting requirements.	☐
Natural cross-flow ventilation minimises the need for fan-forced ventilation.	☐
Early involvement of services engineers ensures efficient space allocation for heating/cooling systems and hot water production. This is often overlooked at the Concept / Resource Consent stage where aesthetics and net floor area / no. of car parks considerations typically dominate.	☐

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Important note: It is highly recommended to include services engineers early in the design of a building to avoid afterthought solutions and potential conflicts such as apex height restrictions, common area impacts, loss of plant efficiency or noise emission issues.

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Building envelope considerations	Considered?
An airtight interior-exterior seal.	☐
Thermal mass in floors and walls acts as a heatsink and keeps temperature more stable. This reduces heating and cooling loads. However, this only effective where the walls and floors are not internally insulated (e.g., precast concrete with wallpaper instead of gib walls on battens with pink batts).	☐
High R-values in the roof and windows insulate the indoor climate.	☐
Avoid thermal bridges (e.g., non-thermally broken windows or continuous floor slabs as balconies).	☐
Employ shading elements, such as traditional eyebrows above windows, and other elements to reduce peak solar heat through glazing.	☐

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Plant considerations	Considered?
Low energy consumption depends on heating/cooling and hot water systems powered by renewable energy sources, matched to actual demand. The actual demand is the max. demand multiplied by a diversity factor, which may be derived from statistics on equivalent facilities or modelling.	☐
Water is an efficient thermal conductor, non-toxic, and environmentally friendly. Pipework for water reticulation can be reused on system replacement whereas coolant gas operated pipework typically requires replacement.	☐
Ground source, air source, and evaporative heat sinks are common renewable energy sources that are regularly used in New Zealand and across the globe.	☐
Ground source systems require flowing water at manageable depth and should balance energy extraction and discharge. The use of ground water directed into cooling systems and discharged back to the ground is discouraged as it requires separate resource consents and ongoing monitoring.	☐
Air source systems need sufficient space for air movement and acoustic separation. Air source heat pump hot water systems can be installed in basements or enclosed spaces but require artificial ventilation which decreases efficiency.	☐
Evaporative heat sinks, like outdoor pools, work well with water-based heating/cooling systems.	☐

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Important advice when considering heating/cooling systems

There are many studies available, and continue to be updated, that demonstrate actual demand, in various use scenarios, while being able to cater for peak demand. Design to peak and application of standard diversity factors such as 0.8 is not a useful way to design. Systems based on water as a medium for the transport of energy from the source to the user is advised. Water has the property of being a good thermal conductor, non-toxic, and non-reactive with the Ozone layer and if released, it does not contribute to the greenhouse effect.

Summary

This guide includes just some of the considerations to be aware of when embarking on a high-energy efficiency building project. Early-stage collaboration between designers and experienced installers ensures compliant and cost-effective project execution and improved energy efficiency throughout a building’s life.

Learn more about Design Management services at WT.

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We’d love to hear from you to discuss this topic further and to answer any questions you may have, please contact Max at max.mayer@wtpartnership.co.nz Discover more about WT including our Project Management, Quantity Surveying, Infrastructure and Advisory Services at wtpartnership.co.nz

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