Active thermal mass enhancement using phase change materials

Abstract

8Buildings account for around 40% of energy consumption in the UK. For over twenty years active thermal mass 9 systems have been a feature in low-energy buildings in northern Europe. By passing ventilation air, and utilising 10 night ventilation, through the hollow core structures efficient heating and cooling has been achieved. Despite 11 the success, such systems suffer from space overheating and efficiency losses during extended hot periods. 12Control strategies have largely mitigated this effect however low cost retrofit solutions that enhance the system 13 are of interest. This research therefore investigates the benefit of using innovative phase change material (PCM) 14 solutions to enhance thermal comfort and reduced energy usage of traditional active thermal mass systems. 15 A prototype PCM enhancement was constructed, with energy saving and comfort benefits investigated under 16 controlled laboratory conditions. In absolute terms the PCM solution offered an additional 12.5% energy storage 17 capacity and a 29% increase in active surface area, coupled with the existing sensible thermal mass. Under 18 laboratory conditions the PCM addition saved an additional 0.1 kWh per day, delayed AC onset by 1.2 hours and 19 offered an average 1.0°C reduction in room temperature during eight hours of fixed cooling load, contrasted 20 against the original active thermal mass system. 21 KEY WORDS 22Active thermal mass, phase change materials, thermal mass, free cooling, night cooling, energy-efficient cooling 23

Thermal Performance of Hollow-Core Slab Ventilation System with Macro-Encapsulated Phase-Change Materials in Supply Air Duct

“…Realizing the potential of both PCM and hollow-core system in improving building energy efficiency and thermal comfort, several studies have investigated the combination of these two technologies to further improve the energy efficiency. Whiffen et al [37] worked on a prototype of hollow-core slab with PCM enhancement and investigated energy savings and comfort benefits under laboratory conditions. Due to the PCM incorporation, additional 0.1 kWh energy was saved per day, with 1.2 h thermal delay and 1.0 • C reduction of room temperature reported compared to the original hollow-core slab.…”

An experimental investigation into the comparative hygrothermal performance of wall panels incorporating wood fibre, mineral wool and hemp-lime

“…Some causes of 'energy performance gap' are recognised as inaccurate estimation of energy use, low construction quality, inadequate building services, mismatch between the specification and the actual construction details, occupants' behaviour and the 'Rebound Effect' where actual energy use is less than what is expected due to behaviour adjustment of the economic agent [15][16][17]. The risk of overheating the UK buildings with regards to future weather scenario and the role of the materials with high thermal inertia is well documented [18][19][20]. As such, the current paper concerns with the thermal and hygric performance of three wall panels with bio-based and mineral materials as the key constituents.…”

Building Energy Management Using Increased Thermal Capacitance and Thermal Storage Management

“…If these methods used permanent installations, such as buildings constructed with a high thermal mass, then benefits could have been lost when a low thermal capacitance is favorable. Due to this, investigations into active thermal mass and thermal storage methods are of interest [14][15][16][17][18][19]. Carpenter et al [16] found building energy consumption reduced when implementing increased thermal capacitance though water circulation in the shell of the building.…”

“…This paper aims to address this issue by introducing phase change materials (PCM) to a water storage tank to reduce tank size with only small reductions to heat storage capacity. Kong et al [18] and Whiffen et al [15] both conducted experiments showing the validity of integrating PCMs for increased thermal mass, Kong et al through passive PCM wallboards, and Whiffen et al though an active hollow slab with embedded PCM. Whiffen et al were able to show a delay in AC onset by 1.2 h. The impact of PCM on building energy consumption has also been studied using numerical simulations using software such as the Transient System Simulation Tool (TRNSYS [20]) [21][22][23][24], which was also used in this paper's study.…”