What is the difference between a Typical new build and a Passivhaus Certified Home?

In the quest for sustainable living and energy efficiency, the terms ‘low energy house’ and ‘Passivhaus certified home’ often merge and homebuyers don’t realise that there is a significant difference. While both concepts aim to reduce energy consumption and environmental impact, they differ considerably in terms of standards, design principles, and performance metrics. Understanding these differences is crucial for homeowners, builders, and policymakers aiming to promote sustainable building practices.

In this article, we will evaluate the key features of both and understand the benefits that a Passivhaus certified home offers above that of a typical new build.

Typical new build ‘Low Energy House’: A Broad Approach

A low energy house is designed to consume less energy than a standard built house. However, the term ‘low energy’ is a relatively broad term and can encompass a variety of building practices and technologies aimed at improving energy efficiency.

Low energy homes typically feature:

• Enhanced insulation in the walls, roofs, and floors to reduce heat loss.
• Double glazed windows and doors that minimise heat transfer.
• High-efficiency boilers and/or solar panels.

While these features collectively contribute to lower energy consumption, the specific standards and practices can vary widely depending on the specification of materials used.

Passivhaus Certified Home: A Rigorous Standard

In contrast Passivhaus, or Passive House, is an internationally certified low energy building model, that results in ultra-low energy buildings that require little energy for heating or cooling and it vastly improves a property’s ecological footprint.

The Passivhaus standard is based on several key principles:

• Thermal insulation that has significantly higher levels of insulation compared to typical low energy houses.
• Airtight construction that provides an extremely airtight building envelope to prevent heat loss and eliminate draughts.
• High performance triple-glazed windows and doors with insulated frames.
• Thermal bridge-free design that minimises heat loss by eliminating gaps or paths where heat can escape through building materials.
• Mechanical ventilation with heat recovery (MVHR) system that recovers heat from exhausted air and uses it to preheat incoming fresh air, maintaining indoor air quality and thermal comfort.

To achieve Passivhaus LEB certification, a building must meet stringent criteria, including:

• Specific heating demand of less than 30kWh per square metre per year.
• For typical new build properties, the airtightness typically ranges from 3 to 5 ACH50. In contrast, Passivhaus LEB designed homes have much stricter airtightness requirements, and must achieve a score of below 1 ACH50.

So, what does this all mean? It means that Passivhaus properties achieve a consistent level of performance, significantly reducing energy consumption and enhancing comfort. Such is the Passivhaus model that each house is independently audited by a third party to ensure it meets this rigorous criteria. This certification method is considerably further advanced in comparison to other new build developments where local building control only check one of each house types in the scheme.

 The Key Differences

1. Standards and Certification: Typical new build houses follow general principles and NI building control guidelines. Passivhaus homes adhere to a specific, rigorous standard with strict certification requirements for low energy buildings.
2. Craftsmanship and Materials: Only high specification materials can be used in a Passivhaus to meet the demanding standards for insulation, airtightness and overall performance, and various tradespeople working on a Passivhaus Certified home undergo specialised training to ensure that every aspect of the construction meets the stringent requirements.
3. Energy Performance: Passive homes carry an EPC A rating based on the overall house construction, not just because of the addition of PV solar panels.
4. Heat Loss: In a Passivhaus certified home over 90% of the heat generated in the home, stays within the home, unlike typical new build houses.
5. Comfort and Air Quality: The airtight construction and MVHR system present in Passivhaus homes ensures superior indoor air quality, consistent thermal comfort and soundproofing. Typical new build houses do not achieve the same level of performance in these areas.
6. Save Money on Utility Bills: On average, utility bills in a Passivhaus home are considerably lower than those in a standard low energy home and sometimes up to 70% lower due to the superior design and build quality.

For those committed to the highest standards of energy efficiency and sustainability, a Passivhaus certified home is the gold standard, and homebuyers are guaranteed a house that is truly low energy that will stand the test of time and save you money.

Fraser Millar is currently developing two Passivhaus developments in South Belfast, visit our Lancaster Park show house and see the benefits for yourself.

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