How does Passive House significantly reduce energy use in buildings?

Passive House reduces energy use by minimizing heat loss and gain through super insulation, airtightness, high-performance glazing, and heat recovery ventilation. It often cuts heating and cooling energy use by up to 90% compared to standard buildings.

What are the key design principles behind Passive House standards?

The five core design principles are: continuous insulation, airtight construction, high-performance windows and doors, thermal bridge-free design, and balanced mechanical ventilation with heat recovery. Together, they create ultra-low energy buildings with excellent comfort.

Why is airtightness crucial for achieving Passive House certification?

Airtightness prevents uncontrolled air leakage, which otherwise undermines insulation and ventilation. Passive House requires ≤0.6 air changes per hour at 50 Pascals, verified by blower door testing. This ensures energy efficiency and indoor air quality.

How do Passive Houses improve indoor comfort and air quality?

They maintain stable indoor temperatures, eliminate drafts and cold spots, and use mechanical ventilation with heat recovery (MVHR) to supply filtered fresh air continuously. This ensures a healthy, consistent indoor environment all year round.

In what ways can existing buildings be renovated to meet Passive House standards?

Existing buildings can be renovated using the EnerPHit standard, which allows for phased upgrades of insulation, airtightness, glazing, and ventilation. It requires careful planning but delivers high energy performance and improved comfort.

How does Passivhaus achieve high occupant comfort with minimal energy use?

Passivhaus combines insulation, airtightness, and MVHR to keep indoor temperatures stable and air fresh, often requiring little to no active heating or cooling. This results in very low energy bills and high comfort year-round.

What are the key differences between Passivhaus and traditional passive solar design?

Traditional passive solar relies mainly on orientation and thermal mass, while Passivhaus is performance-based, using PHPP modeling, airtightness, insulation, and MVHR to deliver consistent comfort and efficiency in any climate.

How has the global adoption of Passivhaus standards evolved over time?

Passivhaus began in Germany in the 1990s and has since spread globally, with increasing uptake in Europe, North America, Asia, and Australasia. Its principles now influence energy codes and building best practices worldwide.

In what ways does the Passive House Institute influence building practices worldwide?

The Passive House Institute sets international benchmarks for energy-efficient design through certification standards, research, and PHPP software. It drives innovation and consistency in high-performance building practices globally.

Can existing buildings be retrofitted to meet Passivhaus standards?

Yes. The EnerPHit standard provides a pathway for retrofitting existing buildings to meet Passivhaus-level performance, through upgrades to insulation, airtightness, windows, and ventilation — even in challenging existing conditions.

Passive House Design Consultancy — BEO Science

BEO Science — Passive House Services

Passive House design consultancy —
from feasibility to certification submission

PHPP modelling, envelope design, thermal bridge analysis, MVHR coordination, and full documentation support across every stage — so your project arrives at the certifier in the best possible condition.

PHPP Modelling Envelope Design Thermal Bridges MVHR Coordination PHI · EnerPHit · LEB NZ & AU

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Looking for PHI building certification? Certification is a separate service — independent quality assurance through design and construction, culminating in the PHI certificate. We offer this alongside design consultancy.

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Why It Matters

Most Passive House projects don't fail at the end — they fail at the beginning

Certification is the last step. The decisions that determine whether a building meets the criteria are made months or years earlier — orientation, form factor, glazing ratios, envelope build-ups, junction details, mechanical system selection. Getting those wrong early is expensive to correct later, and some decisions can't be undone once construction begins.

Form factor and glazing set at concept — without PHPP

A building with a poor form factor or unbalanced glazing distribution will struggle to meet the heating demand criterion regardless of insulation thickness. These parameters need to be tested in PHPP before the design is locked.

Thermal bridges that aren't designed until construction

Junction details are often deferred. By the time thermal bridge values are calculated, the structural decisions that create the bridge have already been made — and remediation requires redesigning elements that are already specified or built.

MVHR specified too late to coordinate with the building

MVHR duct routing, pressure loss, and airflow distribution need to be integrated into the building design — not retrofitted. Late coordination means compromises in duct routing, room-by-room airflow, and heat recovery efficiency.

Window performance assumed rather than specified

Window Uf, Ug, g-value, and installation psi-values all feed directly into PHPP. Generic assumptions at early stage are often replaced with actual product performance at pre-construction review — and the delta can move the energy balance significantly.

Scope of Service

What Passive House design consultancy covers

Our scope is structured around the actual design and construction sequence — not a fixed deliverable list. Optional stages are flagged and scoped separately.

Initial Feasibility and Design Support

Review of architectural drawings and site conditions. Early-stage PHPP setup using design intent and best-practice assumptions. Identification of risk areas — glazing ratios, form factor, orientation, thermal bridge exposure — before design decisions are locked. Coordination with the design team to integrate Passive House principles from the outset, including support for decisions on layout, massing, and building orientation.

PHPP Modelling and Optimisation

Creation of a full Passive House Planning Package (PHPP) model. Detailed energy balance modelling covering space heating demand, cooling demand, and primary energy. Iterative adjustments with the design team to help meet certification targets — including sensitivity analysis identifying which design changes move the result most efficiently. Advice on cost-effective trade-offs between insulation, glazing, and mechanical system performance.

Building Envelope Design

Wall, roof, and floor build-ups designed to meet energy demand and moisture control requirements simultaneously. Insulation specification — thickness, lambda values, vapour permeability, environmental impact. Vapour control and airtightness strategy integrated into architectural detailing. Thermal envelope coordination with structural design to avoid conflicts that create unavoidable thermal bridges.

Thermal Bridge Analysis

Calculation and documentation of key junction psi-values to ISO 10211 using Flixo FEA. Typical details modelled include foundation and slab edge, window and door reveals, roof-wall junctions, and balcony or steel penetrations. Guidance for eliminating or minimising thermal bridging in construction details, with PHPP-compatible psi-value outputs for direct Areas sheet entry. See also our standalone thermal bridge analysis service →

Ventilation and Mechanical Systems Support

MVHR system advice and specification. Coordination with mechanical engineers or suppliers to ensure compatibility with PHPP inputs. Duct routing strategy, airflow assumptions, and pressure loss estimates for the energy model. Documentation preparation for certifier submission — including flow rate adjustment records and system commissioning data.

Window and Glazing Advice

Performance requirements — Uf, Ug, g-value, and installation psi-value. Assistance selecting PHI-certified components or calculating equivalent performance for non-certified products. Support for joinery and installation details, ensuring thermal and airtight continuity at the frame-to-wall junction. Window specification inputs formatted for PHPP.

Certification Documentation Support

Support across all four certification stages — Initial Check, Preliminary Review, Pre-Construction Review, and Post-Construction Review. We provide the full PHPP model and evidence documentation for certifier review, respond to certifier feedback, and assist with clarifications at each stage. Certification is carried out by an accredited Passive House certifier; this scope supports that process as the design consultant.

Construction Phase Support Optional

On-site inspections to verify insulation installation, airtightness membrane continuity, and junction execution. Practical guidance for trades on correct installation of membranes, joinery, and ducting. Responses to site-specific construction queries as they arise. Scoped and priced separately based on project location and inspection frequency.

Blower Door Testing Optional

Pre-line blower door test to identify and resolve leakage before linings are installed — when remediation is still straightforward. Final blower door test to confirm the airtightness target is met for certification. Reporting of ACH @ 50 Pa and input into the final PHPP update. BEO is ATTMA accredited for both L1 and L2 testing.

Who We Work With

Design consultancy across the full project team

Architects & Designers

We work as a specialist building science input to the design team — providing PHPP modelling, envelope advice, and thermal bridge analysis at the stages where it influences decisions. We don't arrive after the design is done.

Homeowners & Developers

For clients commissioning a Passive House build directly, we can engage from feasibility through to certification submission — working with your architect and builder as the building science specialist throughout the project.

Builders & Project Managers

Construction phase support and blower door testing address the practical challenges of building to Passive House standard — not just designing to it. We can advise trades directly on airtightness and insulation installation.

Existing PH Designers

For designers with Passive House experience who need specific inputs — PHPP peer review, thermal bridge calculations, or blower door testing — we offer these as standalone commissions without a full-service engagement.

Standards

All PHI certification pathways

Passive House design consultancy applies across all three PHI building certification standards — the appropriate pathway depends on the building type, existing condition, and project ambition.

PHI certification pathways — all covered

Passive House Classic / Plus / Premium — the full standard for new buildings. Heating demand ≤ 15 kWh/m²a, primary energy demand varies by tier.
EnerPHit — the retrofit standard for existing buildings. Relaxed criteria acknowledge that complete thermal envelope continuity is rarely achievable in refurbishment.
PHI Low Energy Building (LEB) — an intermediate standard between EnerPHit and full Passive House. Suitable for projects where the full standard is not feasible but significant performance improvement is achievable.

FAQ

Common questions

When should Passive House design consultancy begin?

As early as possible — ideally at concept design before the form, orientation, and major structural decisions are fixed. The feasibility and early PHPP stage is the highest-leverage point: design changes are cheap, and the modelling informs decisions that determine whether certification is achievable at all. That said, we can engage at any stage, including reviewing a near-complete design — though the scope of what can be changed decreases as the project advances.

Is design consultancy the same as certification?

No — they're separate services. Design consultancy covers the modelling, envelope advice, and documentation support that prepares the project for certification. Certification is an independent quality assurance process carried out by an accredited Passive House certifier, resulting in the PHI certificate. We offer both — see our Passive House Certification service for the certification scope.

Can an existing home be taken to Passive House standard?

Often, yes — through the EnerPHit pathway. EnerPHit applies relaxed criteria that acknowledge the constraints of refurbishment: complete thermal envelope continuity is rarely achievable when working around an existing structure. Feasibility depends heavily on the existing building — construction type, existing insulation, window replacement feasibility, and services. An early feasibility assessment is the right starting point.

Does a Passive House limit architectural design freedom?

The performance criteria don't dictate appearance — but they do constrain certain parameters. Form factor matters: complex geometry increases the envelope-to-floor-area ratio and makes the heating demand harder to meet. Glazing distribution matters: heavily glazed north facades help; heavily glazed south facades in NZ create cooling risk. These are parameters to design within, not restrictions on aesthetics.

Do you work on commercial and multi-residential Passive House projects?

Yes. The PHPP methodology and PHI certification apply to all building types — residential, multi-residential, commercial, educational, and healthcare. Commercial projects often require additional coordination on occupancy schedules, internal gains, and mechanical systems. We've worked across the full building type range in NZ and Australia.