Civil Engineering Reference
In-Depth Information
buildings to the point that renewable energy can meet the remaining loads. Even
though the freedom of interpretation and of the means to be used are left to the
different member states, a radical improvement in energy efficiency for buildings
will be the most appropriate approach in reducing energy consumption.
Two main approaches for the reduction in energy use in buildings can be
identified: (1) high thermal performance, expressed by a maximum value for heat
demand and (2) limitation of delivered energy, expressed by a maximum value for
primary energy (Dequaire
2012
). The first usually supports the second, while the
opposite is not necessary true. The Passivhaus standard used in the cases presented
in this article is of the first type. The EU directive, and therefore several buildings
codes in Europe, qualifies for the second type.
2.2 Upgrade of Large Buildings
Different reasons can prompt the retrofit of a building, and, independently of any
of these reasons, the opportunity to add other qualities can also be present. For
example, different types of concerns, or the necessity to comply with new laws like
building codes, fire regulations, universal design or heritage, can generate the
different reasons to be taken into account in the retrofitting process. Maintenance
and renovation projects extend from façade painting or window replacement to
structural repair or upgrades of technical installations. Occasionally, a building can
be almost totally rebuilt in cases where, for example, only the concrete structure is
kept. In any case, the size of the building and eventually the large number of users
involved require a good analysis of the project. An economic evaluation of
reconstruction versus demolition and construction of a new building can be rea-
lised. For example, in the case of the municipality of Linz, if calculated retrofit
costs are higher than 80 % of what a new building would cost, then a new building
is constructed (Personal communication, November, 2010).
2.3 Passivhaus
The precise definition is: ''A Passive House is a building, for which thermal
comfort (ISO 7730) can be provided solely by post heating or post cooling of the
fresh air flow, which is required for good indoor air quality (IAQ) (DIN 1946) -
without using recirculated air in addition''.
This is a purely functional definition, which does not contain any numerical
values and is valid for all climates. It clarifies that the Passive House is a fun-
damental concept and not a randomly set standard.
From this initial definition, it is usually assumed that all thermal corrections,
heating or cooling, are provided by the ventilation system, which is necessary to
secure fresh air and remove used air and pollution. In association to the Passivhaus
