Cost-effective Passivhaus

Addressing the effects of inflation and spiralling material costs, we share our top tips on how to keep Passivhaus-related building costs down.

Costs & payback

Passivhaus often requires additional costs for materials, labour and design and certification but this uplift is usually now less than 8%, when factoring in other savings through reduced heating equipment need and economies of scale. This uplift is more than repaid through long-term energy bill savings and whole life costs. In the face of escalating energy bills, the long term lifecycle payback is an increasingly powerful business case argument for Passivhaus.

It is also worth noting that some Passivhaus school projects have managed to achieve the standard with no additional costs.

Zero ambitions podcast

Passive house doesn't have to cost more to build - with Dr Shane Colcough (UCD, Ulster University)

Zero Ambitions podcast spoke with Dr. Shane Colclough, an academic and energy consultant who has written papers sharing fully-costed breakdowns of building to the Passivhaus standard versus building regulations in Ireland and Northern Ireland.

Cost premium for energy saving projects

It is also worth bearing in mind that energy efficient buildings are starting to see a cost premium when valued for the market, with recent research showing that house buyers are willing to pay almost 10% more for energy efficient properties.

Passivhaus looks far cheaper when whole lifecycle costs are analysed

Alun Watkins, Kalm Consulting Services

Building a cost-effective Passivhaus

The UK construction industry as a whole is experiencing price volatility because of higher energy prices and escalating inflation, with market forecasts suggesting that 2023 is going to be a bumpy year. In this context of fluctuating construction material costs, it is important not to confuse 'normal' construction costs with Passivhaus costs.

Intelligent value engineering approaches in the early stages of design are crucial to making Passivhaus cost-effective, given current financial and budgetary challenges.

Easy wins

There are some fundamental principles which can help keep a Passivhaus project's costs on track.

Simplifying the building 'form factor'. Generally speaking, the more compact the building and lower the form factor the greater its energy efficiency, reducing the project's insulation requirements.
Using careful orientation of the building to optimise passive solar gains.
Building at scale, with repeat building designs.
Building more compactly so doing more with the same site footprint.

Passivhaus Trust top ten tips to minimise costs

Designing out avoidable costs

There are many potential avoidable costs on a Passivhaus project that can be reduced by careful planning and value engineering during the early stage design. .

Design early, with Passivhaus as the goal from the outset.
Undertake true value engineering (early-stage analysis of the function of every component in the project), rather than late-stage cost-cutting to rescue a budget.
Use PHPP (Passive House Planning Package) as a value engineering tool for early stage decision-making.
Prioritise function over form (whilst strongly maintaining that Passivhaus buildings can be beautiful!).
Carefully assess window design, which offers great potential for value engineering.
Limit ‘first time’ costs by integrating Passivhaus experience within the project team.
Design out thermal bridges and use of airtightness tapes and membranes, as far as possible
Work closely with contractors and manufacturers from the outset.

We take the approach that 60% of any cost premium for Passivhaus can be designed out.

Emma Osmundsen, Exeter City Living

Retrofit

The EnerPHit standard is unlikely to be suitable or appropriate for all retrofit projects but cost-effective approaches to retrofit keep the key elements of the Passivhaus and EnerPHit methodology, focusing on eliminating the performance gap. The AECB retrofit standard is a ways in which Passivhaus approaches are being applied to retrofits.

Cost-effective retrofit strategies

Whole house retrofits work well on projects with good form factor, such as blocks of flats.
Pragmatic solutions can be found through careful modelling of detailing.
Keep costs down by looking for pragmatic retrofit solutions, eg those which can be undertaken while residents are in situ and without needing wholescale roof replacement or digging down below foundations.
Explore designing to the AECB retrofit standard, where EnerPHit is not possible.

Watch videos

The following talks on the theme of 'How to deliver cost-effective Passivhaus' were presented at the 2022 UK Passivhaus Conference.

Stewart MacLeod, Faithful+Gould 'Market conditions & cost impacts'

Alun Watkins, KALM Consulting 'Design considerations for cost-effective Passivhaus'

Sarah Price, QODA Consulting 'Cost-effective retrofit'

Local authority and housing associations are invited to join us on the 18th January 2023 for an introductory webinar focused on Passivhaus Social Housing. This is an online event - FREE to all social housing providers.