What is the European Passive House (Passivhaus) Standard?

The Passive House (Passivhaus) building standard originated in Germany in 1988 and is a voluntary standard which is overseen worldwide by the Passivhaus Institut in Germany (est 1996). Passive House certified buildings are the most energy efficient buildings worldwide.

A passive house is defined as “a building in which a comfortable interior climate can be maintained without active heating and cooling systems (Adamson 1987 and Feist 1988). The house heats and cools itself, hence “passive”.”

The standard is most often applied to new buildings but is also used for refurbishments of existing buildings.

In European passive house construction the following requirements must be met:

1. an annual heating requirement that is less than 15 kWh/(m²a),
2. total energy consumption of living area may not exceed 120 kWh/(m²a) for heat, hot water & household electricity, and
3. the building must not leak more air than 0.6 times the house volume per hour, as determined by a blower door test.

The key factors in European passive house design are:

1. Compact form and good insulation,
2. Southern orientation and shade considerations,
3. Energy-efficient window glazing and frames,
4. Building envelope air-tightness,
5. Passive preheating of fresh air,
6. Highly efficient heat recovery from exhaust air using an air-to-air heat exchanger,
7. Hot water supply using regenerative energy sources, and
8. Energy-saving household appliances:

Comparison of Energy Ratings of Homes in Europe. *

WSchVO = German Heat Protection Regulation SBN = Swedish Construction StandardThe Passivhaus Institut has developed “The Passive House Planning Package” (PHPP) which provides everything needed to design a properly functioning Passive House including tools for:

1. calculating energy balances (including U-value calculation)
2. planning the windows
3. designing the comfort ventilation system
4. determining the heating load
5. estimating the summer comfort, and
6. designing the heating and hot water supply

Passive Houses are built from a wide range of materials and use many different construction techniques, however attention to detail to ensure a “continuous uninterrupted airtight building envelope” is essential. The Passive House Planning Package (PHPP) includes a construction manual with detailed techniques to achieve this.

Passivehaus certification of completed buildings worldwide is overseen by the Passivehaus Institut to ensure that buildings will perform as specified to the standard. Currently there are over 30,000 such buildings mainly in Europe.

Links:

1. Passivhaus Institute – Germany
2. BRE Passivhaus UK
3. BRE Passivhaus primer
4. Passipedia, the Passive House resource

* Published by The Passivhaus Institut.

The heating and cooling potential of roof space air using positive pressure ventilation systems: is it effective?

Positive pressure ventilation systems are usually designed to extract air from within a building for a specific purpose e.g. to remove moisture from bathrooms, odours from toilets and both moisture and odours from cooking areas in kitchens.

 Positive pressure ventilation systems that draw air from roof spaces and distribute this air through a house have also been available. These systems were originally developed in the UK to try and address condensation problems in old damp houses by taking drier air (lower humidity) from the roof space and blowing this air through the house to try and remove the dampness and mould that had become embedded in the building structure. The air would then leak out through the gaps and cracks in the walls, windows and doors in the building. No claims were made that these systems could heat or cool a house as well.

Recently claims that these systems could effectively heat and cool a house have been made. However a recent study by the University of Otago New Zealand titled ” Heating and cooling potential of roof space air: implications for ventilation systems. “ for the Energy Efficiency and Conservation Authority (EECA) of New Zealand has shown such claims to be unsubstantiated.

The study showed that ” that small potential heating and cooling benefits were possible at certain times from pumping air from the roof space into the living areas of some New Zealand houses. However those potential benefits were not large enough to significantly alter the indoor air temperature on average.”

and that ” the majority of the time, it was calculated that pumping air from the roof space into the house would provide no heating or cooling benefit. In fact, this would often actually act to push the internal temperature further away from the desired level rather than closer to it.”

The report ” recommended that existing positive pressure mechanical ventilation systems should not be promoted and marketed on their heating and/or cooling potential.”

Read the report: Heating and cooling potential of roof space air:         implications for ventilation systems

Pub.

May 2011.

Low Energy Building – is there a standard

In a report “Low Energy Buildings In Europe: Current State of Play, Definitions and Best Practice”low-energy buildings are defined as “…typically using high levels of insulation, energy efficient windows, low levels of air infiltration and heat recovery ventilation to lower heating and cooling energy. They may also use passive solar building design techniques or active solar technologies. These homes may also use hot water heat recycling technologies to recover heat from showers and dishwashers.”

With the accelerating trend to low energy building throughout the world many terms are currently used to describe the desired end result. This can often create confusion as well as mislead as the there is no global standard and regulations vary from country to country.

A European survey undertaken in 2008 identified:

“…17 different terms in use to describe such buildings used across Europe, among which the terms
low energy house, high-performance house, passive house / Passivhaus, zero carbon house, zero energy house, energy savings house, energy positive house, 3-litre house etc. In the relevant literature, additional terms such as ultra-low energy house can be found. Finally, concepts that take into account more parameters than energy demand again use special terms such as eco-building or green building.”

Such confusion can be understood when comparing the passive house / Passivhaus approach which aims to reduce energy consumption by appropriate design and construction techniques so as to minimize the requirements for heating, cooling and ventilation and the concept of zero net energy with its strong emphasizes on using locally generated renewable energy sources to replace grid reliant energy. Both approaches have the same desired outcome i.e. low energy use, but the end result may be totally different in terms of building performance and, occupant comfort and satisfaction.

 

pub. California Energy Efficiency Strategic Plan Jan. 2011 update

Indeed within the concept of zero net energy, there is the energy harvest” versus “energy conservation” debate, as the end result can be achieved with a conventional house with sufficient renewable energy sources or design and construction techniques that minimizes energy usage and requires less renewable energy. The European Council for an Energy-Efficient Economy in a review paper titled “Steering through the maze -Nearly zero energy buildings: achieving the EU 2020 target” in Feb. 2011 stated ” Despite the excitement over the phrase “zero energy,” we lack a common definition, or even a common understanding, of what it means ”

A paper delivered at the Renewable Energy Research Conference 2010 Trondheim, Norway called “User Evaluations of Energy Efficient Buildings” by Hauge, Åshild Lappegard; Thomsen, Judith; Berker, Thomas, showed that more education is required to enable people to better understand the concepts and technologies utilized in low energy building. It is also called for long-term studies to be undertaken to ensure that such low energy buildings do perform as planned. Education is seen as critical for the success of low energy building worldwide and the standardization of terminology and regulations would play a significant part in achieving this.

Currently an emerging de facto standard is the passive house / Passivhaus standard which originated in Germany in 1988. This is a measurable standard and long-term studies have been undertaken of the performance of buildings certified with the standard.