# Testo 635 – U value Measurement On A Wall Of Unknown Materials

Hello my name is Martin Keebler
and I am the owner of the engineering consultancy bow expert we work in the
central western region of Germany advising customers and carrying out
measurements and surveys in the case of this building we intend to provide
advice on energy modernization to do this we need to know the heat insulating
capacity of the existing walls today we’re going to conduct a u-value
measurement with a measuring instrument test of 635 we’ve been told that the
walls of this building are made of different materials thermography has
confirmed this these two walls also have no openings of any kind no windows so we
can’t simply measure the thickness of the wall however the owner doesn’t want
us to drill any holes we’re therefore going to determine the
u-value non-intrusively with a measurement in order to determine the
u-value we need three temperatures which then come together in this measuring
instrument first of all the outside temperature which is recorded and
forwarded by this wireless probe the surface temperature on the interior side
of the wall is recorded with this three wire temperature sensor
the air temperature inside the room is measured with this integrated sensor three measurement points allow us to
take mixed masonry into account the three wires of the surface probe are
attached to the wall using putty They should be arranged in a roughly equal
lateral triangle with edges of about 10 to 15 centimetres after attaching the
sensor and switching on the instrument we go outside for a meaningful measurement it needs to
be cold outside and heated inside there should be about 15 Kelvin temperature
difference this wall is ideal it faces North’s or sunshine can’t falsify the
measurement I now connect the measuring instrument to the computer by USB I then
start the software the instrument is recognized and the
measurement begins the measurement has been running for
about an hour here we can see the last twenty minutes and you can see the curve
of the u-value approaching a final value you can call up the more accurate value
from the statistical calculation and the U value here is around 1.4 PMS on Tector the measurement showed
that the u-value is even worse than we thought it doesn’t meet today’s
requirements at all we are now in a position to be able to suggest suitable
insulation measures