Retrotec USACE - Manual (Page 399)

Appendix K K11
K.6.1 Recommendations
From a thermal point of view, old buildings generally have a whole coherence of
their indoor distribution, which must not be disturbed by indoor transformation.
K.7 Subsystems: Equipment and Occupants
In new buildings, HVAC equipments generally constitute an important means
of regulation of indoor thermal comfort (mechanical ventilation, artifi cial light-
ing, heating and cooling). In old buildings, they are rarely used. This means
that there is an important potential of energy saving (renovation of decayed
heating systems, use of renewable energies, etc.).
Many old buildings do not have ventilation systems. In fact, the openings
allow natural ventilation because of their air permeability. In some cases, air
extraction systems were simply added in the wet rooms.
Current heating systems are various in old buildings. However, there is
often decayed equipment with low energy effi ciency. The technical character-
istics of old equipment are sometimes unknown.
Auxiliary heating systems are numerous. For instance, stoves or chimneys
initially constituted the only heating. These auxiliary systems were adapted to
the thermal behavior of the old building and used by occupants in an intermit-
tent heating mode, according to the thermal inertia.
The occupants infl uence the energy performances of buildings by their
thermal management; generally limited to the regulation of indoor comfort
temperature and of air ventilation. The thermal behavior depends on the oc-
cupancy scenarios. Occupants change their occupancy strategies according to
variable climatic solicitations more often than occupants of an insulated new
building do.
All year round in these old buildings, the thermal inertia phenomena have
a strong infl uence on occupancy scenarios and on the thermal regulation.
This bioclimatic behavior of old buildings has an impact on the occupants’
behavior. They can act on the closed environment to control their thermal com-
fort. In addition, such bioclimatic characteristics directly improve the adaptive
comfort for occupants without using energy HVAC equipment.
K.8 Conclusion
Old buildings have complex energy behaviors. In spite of an apparent heteroge-
neity of the traditional ancient architecture, a strong correlation exists between
outside and inside climates. This correlation is due to the bioclimatic character-
istics of old buildings and to the specifi c adaptive behavior of occupants.