.:: Passive-On In Detail ::.

The Passivhaus Standard

The last ten years has seen increasing interest in Central and North Europe in the Passivhaus construction standard, particularly in Germany. Homes built to the Passivhaus standard are buildings which assure a comfortable indoor climate in winter without the need for a conventional heating system. To permit this, it is essential that the building's space heat load does not exceed 10 W/m² living area in order to be able to use a simple air preheater. Simulations and measurements have shown that for a typical German climate such a design leads to an annual demand for space heating of 15 kWh/(m²a). Homes built to the standard therefore require roughly 85% less energy to heat that a house built to existing German building regulations.

The standard has been named "Passive House" because the passive heat inputs - delivered externally by solar irradiation through the windows and provided internally by the heat emissions of appliances and occupants - are nearly sufficient to keep the building at comfortable indoor temperatures throughout the heating period.

Importantly the Passivhaus standard is defined such that the extra costs of construction are repaid over a reasonable time period through the reduced heating bills in a typical Northern European climate. The solutions adopted are readily integrated in house designs which do not differ significantly from current buildings in terms of aesthetics, layout or construction techniques. They are therefore well accepted by families and attractive to developers.

In Europe as of 2007 more than 8.000 buildings had been successfully constructed to the Passivhaus standard. Positive feedback from inhabitants has confirmed what has been projected; not only utility costs can be reduced drastically, but also the comfort of living increases significantly through energy efficient construction.

Objectives of Passive-On

The Passive-On project has examined how to take the Passivehaus concept forward, especially in Southern Europe. In these regions the problem of household energy use is one not only of providing warm houses in winter but also, and in some cases more importantly of providing cool houses in summer. The Passive-On project has lead to three major outcomes:

1. Design Guidelines: for architects and designers (particularly small studios) the project has developed Design Guidelines for developing cost effective, relatively low investment cost, all season Passive Houses in both heating load and cooling load climates. The Guidelines are targeted at small architectural studios, typical of Italy Spain, and Portugal which have few resources for developing innovative designs and tend to stick with old proven solutions. An integral part of the Design Guidelines is the Planning House Package (PHPP) Software developed by the Passivhaus Institut in Germany. The Passive-On project has extended the PHPP software to calculate cooling loads and evaluate passive cooling solutions.

In extending the concept of the Passive House to the Mediterranean region, the project has evaluated the definition of the Passivhaus Standard as applied in Central Europe, and seen how this might be modified to take into account cooling loads and other end uses within the home.

2. Policy Proposals: The Passive-On project interviewed over 60 professionals from the private and public sectors in the five partner countries active in developing low energy housing. Based on their considerations and from best practice across Europe, the project has collected a number of Policy Proposals to assist the development of Passivhauses. For example:

Training and Development: Training and instruction needs to be improved from the architect to the builder:

- Architects need to improve their understanding of building physics such that low energy and passive design becomes integral to all architectural training and not left as an optional subject for the select few.
- Builders need to improve their understanding and attention to detail to ensure low design solutions are correctly implemented on-site.

Regulation: Building codes need to be addressed to remove some of the implicit barriers to low energy housing:

- High insulation levels means that for the same land footprint as a standard house a Passivhaus will have less useful surface area; council fees and rates should be based on net not gross house volume.
- National norms for summer indoor comfort levels should not be so restrictive as to require active air conditioning.

Financing: The pubic sector can work with private institutions to develop mechanisms to finance the extra cost of purchasing Passivhauses:

- Mortgage schemes can be made to reflect the increases household liquidity of Passivhaus home-owners.

- Articulating architect and design fees to the measured household energy performance can ensure actual performance matches planned.

Accreditation: Providing independent certification for Passivhauses provides the foundations for most other incentive mechanisms. Accreditation schemes can be extended to cover products and or actual builders and in doing so provides an immature market and “untried” product with a quality control and a guarantee.

These and the other proposals as detailed in the set of six Policy Actions Sheets prepared by the Passive-On project require time to implement but experience from around Europe shows that they are feasible when there is the political will to lead in partner and none partner countries.

3. Dissemination: Finally the project has worked hard to disseminate the concept of the Passivhaus standard in countries partner to the project amongst the target audiences (architects, designers and local government). Separate Technical and "Political" Workshops were undertaken in each partner country.

Passive-On was co-ordinated by the end-use Efficiency Research Group at the Politecnico di Milano.

The project ran from the 1st January 2005 to the 30th September 2007.