Industrialised, Integrated, Intelligent sustainable Construction - I3con

HANDBOOK 2 SUSTAINABLE CONSTRUCTION
• Monitoring indoor air temperature and relative humidity. A combination of temperature and
relative humidity is used to evaluate whether there is a risk of fungi growth on the inner
surfaces of the building.
• Monitoring energy consumption for room heating. The building owner may use these data to
alter the behaviour of the inhabitants so that energy is saved.
Most of the above mentioned
items are strongly correlated
with measuring relative
humidity and moisture. The
moisture level in construction
materials or in the indoor air
is an excellent indicator for
damage and unhealthy indoor
climate. Another common
denominator for these items is
that moisture related damage
generally develops slowly
over time. Hence, it is
difficult to detect unless you
are recording data over time,
which is impossible with
conventional methods.
Figure 7. Installation of wireless sensor in lightweight concrete wall next to water installation
Therefore, the wireless RH sensors are ideal for such applications where continuous monitoring is
needed. First of all it is important to determine the most suitable location of sensors in order to catch
the most critical damage (Fig. 7). Secondly, the decision making needs tools so that the risk of
damage or unhealthy indoor climate is assessed in a scientifically sound manner. Both these aspects
are dealt with by experts in building materials and indoor climate.
Applications in concrete production
In connection with concrete castings there may be a need to monitor the concrete temperature in a
structure for a number of reasons:
• Firstly, it may be used to evaluate the maturity and strength of a concrete pour in order to decide
time of formwork stripping and/or prestressing. The use of temperature registrations combined
with age is converted into maturity, which again is related to the strength development and
degree of hydration of concrete (Nielsen 2007). These principles are applicable to cast-in-place
structures and precast concrete products.
• Secondly, the temperature difference between the core of a casting and the surface should not
exceed a certain limit due to the risk of early-age thermal cracking. This is especially a concern
of massive cast-in-place structures where the heat of hydration escapes slowly. On-line
monitoring of critical cross-sections could help eliminate the risk of early-age cracking and
improve the durability of the structure.
• Thirdly, temperature monitoring on the building site and on the formwork and reinforcement
could be suitable to control active measures such as embedded cooling pipes or heating wires or
it may help to warn against freezing conditions prior to casting.
Generally it is a difficult task to establish a conventional temperature monitoring system by means of
thermo couples due to the need for wiring and data loggers. Often the temperature readings are not
gathered and investigated until weeks after the casting took place. This means that these readings
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