Early-stage optimal design of hybrid GEOTABS buildings in terms of costs and CO2 emissions. (1st April 2022)

• Record Type: Journal Article
• Authors: Sharifi, Mohsen; Cupeiro Figueroa, Iago; Mahmoud, Rana; Himpe, Eline; Helsen, Lieve; Laverge, Jelle
• Is Part Of: Energy conversion and management. Volume 257(2022)
• Publication Date: 2022-04-01
• Subjects: Cost-optimal design -- CO2 emission reduction -- GSHP -- TABS -- hybridGEOTABS; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2022.115392
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: Ground source heat pump coupled to thermally activate building structure is GEOTABS. GEOTABS embeds thermal energy storage and can shave building thermal peak loads. GEOTABS design is complex and extremely important at the early-design stage. A design procedure is presented that facilities optimal early-stage design of GEOTABS. GEOTABS can save up to 19% total cost through operational costs saving. Abstract: The high potential of ground source heat pumps (GSHP) to reduce the carbon dioxide emissions of heating, ventilation, and air conditioning (HVAC) systems has been widely acknowledged. GEOTABS combines GSHP systems (which generate heating and cooling) and TABS (thermally activated building structure) systems as storage-integrated emission systems. GEOTABS has been proposed to improve GSHP performance while potentially decreasing investment cost. Moreover, implementing a secondary system in parallel with GEOTABS extends the applicability of these systems to a larger variety of buildings. This combination is referred to as hybridGEOTABS. The dynamic behavior of TABS introduces challenges in the design of these systems including a) thermal comfort uncertainty (typically when fast disturbances occur), b) determining optimal load split between GEOTABS and the secondary system, and c) complexity in sizing the production units. In this paper, a novel dynamic simulation-based design methodology is proposed. The methodology incorporates advantages of TABS such as load-shifting and peak-shaving and produces Pareto optimal solutions. The methodology is applied to nine case studies with variable electricity prices and carbon emission dioxide factors. Results show that the optimal load split is found near the maximum physically possible share of GEOTABS. Consequently, the near-optimal design of hybridGEOTABS can be achieved using simple guidelines without solving an optimization problem. Moreover, the results show that GEOTABS always provides carbon dioxide emission savings of up to 85% but requires higher investment costs of up to 238% that of conventional systems. However, due to the operational cost savings of up to 76%, the use of GEOTABS achieved net present cost (NPC) savings of 2% to 19% in five out of the nine case studies, for 25 years of operation. Finally, it was observed that this NPC is highly sensitive to building design and economic parameters. Hence, an early-stage design analysis with iterations between the HVAC designer and the architect should be performed using case-specific economic parameter values.