Temperature is one of the biggest Facility Managers’ headaches. A high percentage of the complaints an FM Department receives are related to workspace temperature. If we add to this the complaints regarding the noise generated by the HVAC systems, we can conclude that this system will probably get an award for the most usual cause of negative comments in building management.
They are not just employees’ complaints, but also complaints coming from the C-Suite. From the 350,000 kWh that represents the average annual consumption of an office building in Madrid, 75% are consumed by the HVAC system, so taking good care of this system has a direct influence on the Facility Management Department’s costs. Not only does it influence on costs, but also on the environmental impact of the building.
Amongst the multiple solutions that can be used in new constructions for this matter, today we talk about thermo-active structures. This system leaves temperature control to mass, not air. It is quite simple, construction wise. Water circuits are embedded in a concrete slab and the temperature of the concrete can be regulated by the temperature of the water. The slab becomes a convective radiant element, using the concrete thermal inertia. The water just needs to be at 30ºC to warm-up a room, which is a significant difference with the 60ºC that a radiator system need. The floor can be used to warm the room up in winter and the ceiling can be used to cool it in summer.
This way, all the slab surface helps with temperature control, which prevents thermic stress: there are not much cooler areas than others, as it happens with air systems. At the same time, disassociating air and temperature, acoustical stress is also prevented, since it’s not necessary to renew air because of its temperature, just for its quality, which gets solved with CO2 sensors that detect when renewal is necessary. This, just by itself, implies energy savings.
Let’s see specific data. A pilot project developed by the Danmarks Tekniske Universitet – DTU and the Middelfart Sparekasse (a savings bank) used thermo-active structures at the bank headquarters, which had 5,380 sqm. (You can check the project here http://www.archdaily.com/57217/middelfart-savings-bank-3xn/). The goal was cutting electrical consumption coming from heating, cooling and air circulation in 75-80%, so it was easier to fulfil the energy requirements Danish Law demands.
After building completion and occupation, technical monitoring and satisfaction surveys about interior environment were carried out. Electrical consumption due to heating, cooling and air circulation was reduced by 12-13 kWh/m2/year, which meant a 60%. It should be taken into account that this building has a large glass façade, so in different type buildings savings can be even higher.
Regarding satisfaction surveys, their results showed that 85-90% of occupants were satisfied or very satisfied with the thermic, acoustics and environmental conditions of the building.
Another advantage that should be noted is that with this system construction costs get reduced, since the extra charges related to water circuits and control system are compensated with the savings coming form not installing an HVAC system. On the other hand, it makes the design phase easier too, because it makes it easier to fulfil energy consumption requirements demanded by law.
In Spain we have a good example of thermo active structures at IDOM headquarters in Madrid, which is an office building with 10,000 sqm above ground level and 7,000 sqm below ground level. At this building, thermo-active structure, together with other energy saving passive strategies (solar protection elements, opening orientation, natural light optimization, good insulation, etc.), has achieved that primary energy consumption is 75 kWh/m2 against the 240 kWh/m2 that this building’s operation would need with conventional systems, which means 70% in savings. (Source: http://www.construction21.org/espana/data/exports/pdf/idom-acxt-sede-de-madrid.pdf)
All this information makes thermo-active structures systems very attractive from the Facility Manager´s point of view. Not only can we get significant savings but we can also get a more pleasant environment for the occupants, improving their quality of life and their productivity as employees.
> Photo by: RBean http://bit.ly/1GdDwQB