ASHRAE Journal - February 2012 - 52

The main goals were the continuity of the relative humidity, as well as the avoidance of noise and dust. The solution takes advantage of the cooling ability of the concrete core (TABS) (Figure 5). The main objective of this project was not the phase shift of the cooling into the night hours. On the contrary, as the freely available cooling potential of the groundwater is always accessible and the phase shifting would cause temperature swings with too large amplitudes, the cooling is applied over the entire day. The cooling medium is a water circuit embedded in 24 posts 18 m (59 ft) deep in the ground with large layers of groundwater. All the exterior walls of the building are equipped with plastic pipes and exterior insulation to completely cut the connection with the exterior climate. The only connection is through the outdoor air supply. For this, a volume ﬂow rate of 750 m³/h (443 cfm/min) is used. The incoming air will be supplied to the building with a constant temperature and humidity through displacement ventilation slits. More examples of North American buildings are in ASHRAE’s High Performing Buildings magazine and in Reference 12.

Conclusions
Main advantages to thermo active building systems include: • The cooling demand is distributed over a longer period during the day and shifted from daytime to nighttime. This

leads to lower peak loads, allowing the use of conditioning plants of reduced sizes. • By avoiding suspended ceilings, the building height can be reduced, which results in signiﬁcant savings of building materials; • It is possible to use heating/cooling systems with temperatures close to room temperature, which increases the energy efﬁciency of heat pumps, condensation boilers, solar collectors, ground heat exchangers; • For cooling purposes, night ventilation can be used; and • Low installation costs, low operation costs and maintenance costs are possible. The requirements of thermally active systems include: • Active thermal slabs are mainly used in multistory buildings; • Absence of suspended ceilings requires alternative acoustical solutions due to the relative low cooling capacity; • The building design is critical: adequate solar radiation screens are needed, as well as good envelope thermal insulation to keep external heat gains below 1 W/(m²·K); • If TABS is used in walls and ﬂoors (no insulation toward the room), the absorption of diffuse and direct sunshine will increase the cooling capacity signiﬁcantly.

References
1. Meierhans, R.A. 1993. “Slab cooling and earth coupling.” ASHRAE Transactions 99(2). 2. Meierhans, R.A. 1996. “Room air conditioning by means of overnight cooling of the concrete ceiling.” ASHRAE Transactions 102(2). 3. ISO 11855-2 (2012): Building Environment Design—Design, Construction and Operation of Radiant Heating and Cooling Systems – Part 2: Determination of the design heating and cooling capacity. 4. Olesen, B.W., et al. 2006. “Dynamic evaluation of the cooling capacity of thermo active building systems.” ASHRAE Transactions 112(1). 5. ISO 11855-4 (2012): Building Environment Design—Design, Dimensioning, Installation and Control of Embedded Radiant Heating and Cooling Systems – Part 4: Dimensioning and calculation of the dynamic heating and cooling capacity of thermo active building systems (TABS). 6. ENISO 7730 (2005): Moderate thermal environments—determination of the PMV and PPD indices and speciﬁcation of the conditions for thermal comfort. 7. Kolarik, J. 2011. “Simulation of energy use, human thermal comfort and ofﬁce work performance in buildings with moderately drifting operative temperatures.” Energy and Buildings 43(11):2988–2997. 8. Toftum, J. 2008. “Occupant Responses and energy use in buildings with moderately drifting temperatures,” p. 145. Atlanta: ASHRAE. 9. Olesen, B.W., K. Sommer, B. Düchting. 2000. “Control of slab heating and cooling systems studied by dynamic computer simula-

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tions.” ASHRAE Transactions 108(2).
10. ISO 11855-3 (2012): Building Environment Design—Standards for the Design, Construction and Operation of Radiant Heating and Cooling Systems – Part 3: Design and dimensioning. 11. Olesen, B.W., F.C. CurroDossi. 2004. “Operation and control of activated slab heating and cooling systems.” CIB World Building Congress 2004. 12. Kiel, M. 2010. Thermally Active Surfaces in Architecture. Princeton Architectural Press. February 2012

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ASHRAE Journal

ASHRAE Journal - February 2012

Table of Contents for the Digital Edition of ASHRAE Journal - February 2012