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