The legislative and regulatory framework concerning building design has evolved
significantly since the early 2000s. The European Union has drawn attention to the fact
that buildings are responsible for 40% of final energy consumption - and 75% of them
are still energy inefficient - requiring member states to make a major efficiency recovery
through mandatory enforcement directives. On the other hand, this action must not be to
the disadvantage of the comfort and well-being of building occupants, also in view of the
high proportion of time spent indoors.
IEQ - Indoor Environmental Quality
In recent years, the concept of “indoor environmental quality” (or IEQ) has become
established, a global approach with four dimensions:
• thermo-hygrometric comfort;
• air quality;
• visual comfort;
• acoustic comfort.
Several scientific studies have shown that indoor environmental quality has a direct effect
on the comfort, health, well-being and productivity of a building’s users.
Visual comfort
To allow people to carry out visual tasks safely, efficiently and accurately the lighting
function must be correctly designed. The basic requirements are:
• adequate lighting to ensure safety and movement;
• conditions to facilitate visual performance and colour perception;
• acceptable visual comfort for those using the space.
The criteria to be adopted will of course vary according to the activities to be carried
out in a certain environment, but must in any case ensure comfortable visual conditions.
By “visual comfort” we mean a condition of subjective visual well-being induced by
the lighting environment, as indicated by the UNI EN 12665 standard. In providing the
condition of visual comfort, the design of the lighting environment must consider two
factors:
• visual performance;
• environmental pleasantness.
Visual performance is defined by the speed and accuracy with which the task is carried
out, which is why the illuminance and brightness in the environment and on the reference
level are crucial, but other factors such as the size of the visual task and the distance from
the eyes also come into play. However, there is also a subjective element, represented
by the visual capabilities of the individual person. The pleasantness of the environment
reflects the general sensation perceived in an environment and is therefore influenced by
various factors such as the spatial and functional characteristics of the environment, the
person’s preferences, attitudes and psychological aspects and the different contributions
made by natural and artificial light.
High-quality environments, lower costs
The largest cost in today’s organisations is generally the staff and consists of salaries,
health care contributions and induced social costs: surprisingly it can be up to ten times
higher than the cost of workstations. Poor quality environments lead to more frequent
absences, which cause a cost increase under the heading ‘staff’. In minor cases, these
are temporary illnesses and indispositions, but if neglected, they can lead to more serious
consequences. Sick Building Syndrome (SBS) is not uncommon. In this case, specific
illnesses cannot be identified, but people do suffer from conditions that appear to be
related to their time in the building and which tend to disappear when they leave.
Indoor space quality
VISUAL COMFORT
INDOOR AIR
QUALITY
THERMAL
COMFORT
LIGHTING
ACOUSTICS
IEQ
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Source: BPIE
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Investment value
A building with a high quality interior not only has a positive eff ect on the people who
spend time in it, but can also be a good investment. According to recent research,
there are at least three benefi ts:
• Increased building value; An excellent indoor environment translates into a value
up to 8% higher than a standard building and the ‘price premium’ that the market is
willing to recognise will increase in the coming years;
• a higher rental income for the whole or parts of the building of 5-10% more;
• a higher occupancy rate (around 10%) of the working environment.
(source: REHVA Journal)
Typical operating costs
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90%
Personnel costs
Rentals
Energy
9%
1%
Productivity impact of building-related elements (source: BPIE)
Element
Impact on productivity
Context
Illumination
7% to 26% improvement in the learning process in environments
with high levels of daylight compared to those
with low levels of daylight
Schools
Improvement of the learning process by approx. 20% with
additional access to daylight (via skylight)
compared to rooms without daylight
30% increase in reading speed
thanks to activating cold light
30% increase in concentration
thanks to biologically optimised light
reduction of the average length of stay (hospitalisation)
between 16% and 41% in rooms
with a high daylight level
Hospitals
Air quality and
lighting
Significant progress in cognitive functioning
with improved air quality and lighting conditions
Offices
SMART LIGHTING
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