passivhaus principles

What is the definition of Passivhaus?

How does it achieve comfort and what are the main objectives?

Ultra low energy building standard, designed to minimise heating and cooling demand.

It achieves comfort through height insulation, airtight construction, reduce thermal bridges, high performance glazing and controlled ventilation.

The main objectives is to reduce energy consumption, improve indoor comfort, lower carbon emissions and improve indoor air quality.

What is the heating energy balance?

What is the target heating demand?

Passive house design aims to balance heat gains and heat losses with minimal additional heating

Heat gains being solar gains and internal gains like occupant, lighting and equipment.

Heat losses include infiltration, ventilation, thermal bridges, walls, floors and windows.

less or equal to 15kWh/m²/yr

Explain how shape and building form affects the energy balance

Compact forms reduce expose surface barrier therefore lower heat is lost. SA:volume ratio is directly proportional to heat loss.

Complex building forms require more insulation and higher construction cost

Explain how thermal bridges affect the energy balance.

Define, give examples, what are the problems it creates and what is the aim?

Thermal Bridge is a material, component or gap passing through insulation layer that allows heat transfer (e.g. Rafters through insulation, timber studs, can’t leave structures, lintels, gaps between insulation boards)

This creates problems like increased heat loss, lower energy consumption, surface condensation risk, mould growth risk and reduce in comfort.

The design aim is to minimise or eliminate thermal bridges

Explain how high performance envelope affects the heating energy balance?

What are the four key requirements and it’s purposes?

Continuous whether barrier protects against water and prevents wind entering insulation.

Continuous insulation maintains uninterrupted insulation layer.

Continuous air barrier controls moisture and reduces uncontrolled airflow.

Minimum thermal bridging prevents heat bypass paths

Explain how glazing and orientation can affect the heating energy balance?

These include triple glaze windows, thermally efficient frames and careful placement within the insulation layer. This helps lower heat losses, improve comfort and reduce condensation risk. In a typical timber window value, the glass provides 0.6W/m²K and the frame provides 1.4W/m²K. The rule of thumb is you should have more glass and less frame area to improve performance.

Orientation effects like south facing windows help maximise winter solar again and is easier for some shading which allows heating demand to increase from the south. You can do this by orientating the building away from south where the larger angle means a larger heating increased percentage.

Explain why air tightness is important and what is the Passivhaus requirement

Air tightness prevents cold drops, reduces heat loss, improves comfort, prevents thermal bypass, reduces condensation risk, reduces mode growth and improve durability.

The passive house requirement is n50 is less or equal to 0.6 ACH at 50 Pa pressure

Explain why highly insulated building envelopes affect the heating energy balance

Building elements require very low U-value to reduce heat transfer. Super insulated walls, roof and floors reduce heating demand.

Typical characteristics like thick insulation layers, continuous insulation around the building envelope and minimal gaps between insulation help reduce heat loss in winter and heat gain in summer

Explain why ventilation and mechanical ventilation with heat recovery (MVHR) affects the heating energy balance?

What are the advantages and design considerations

The MVHR purpose is to supply fresh air while recovering heat from extracted air.

Advantages like reduce heating demand, better indoor air quality and improved comfort.

Design considerations like heat exchanger location, filter access, noise control, duct layer and return air paths.

It is important as a type buildings require controlled ventilation systems.

Explain the different certification standards.

Talk about the heating demand and renewable generation

Passivhaus classic has a heating demand of 15kWh/m²yr per 60kWh/m²yr.

Passivhaus plus has a heating demand of 15kWh/m²yr per 45kWh/m²yr with a renewable generation of 60kWh/m²yr.

Passivhaus premium has a heating demand of 15kWh/m²yr per 30kWh/m²yr with a renewable generation of 120kWh/m²yr

What is the basic thermal and energy requirements of passive house?

Passive house heating demand must be less or equal to 15kWh/m²/yr to minimise heating energy use.

Maximum heating load requirement of 10W/m² to allow very small heating systems

The typical ventilation requirement is about 30m³/hr/person

Explain the House at Cornell Tech case study and what Passivhaus principles it includes

It is a residential student accommodation building with the worlds tallest residential certified passive house building of 26 story high-rise building.

High-performance facade of pre-fabricated insulated facade panels to reduce heat losses through envelope, efficient ventilation system, airtight and insulated envelopes to reduce infiltration losses and improve comfort throughout the year, low energy heating and cooling systems allows excellent indoor air quality, stable temperatures, lower energy and reduce carbon emissions.

Overall integrates Passivhaus principles of continuous insulation, airtight construction, efficient glazing,, heat recovery system systems and reduce heating demand.

Explain the Oakmeadow Primary School case study and what Passivhaus principles it includes

Passive house school building in the UK.

It includes highly insulated envelopes to reduce heat loss during winter and limits over overheating in the summer, triple glaze windows to improve the performance, brise soleil solar shedding to control solar gains and reduce overheating risks, heat recovery ventilation to provide fresh air into classrooms, natural summer ventilation like opening windows and ventilation panels allows direct external airflow.

Overall integrates passive house principles of continuous insulation, sole gain control, tight construction, heat recovery ventilation and reduce heating demand to create a comfortable learning environment, with good indoor air quality and lower energy consumption