On the Influence of Thermal Mass and Natural Ventilation on Overheating Risk in Offices

Abstract

Free cooling strategies are gaining importance in design practice due to the increased risk of overheating in well-insulated buildings with high internal loads such as offices. The state of the art highlights that the most efficient passive solution for indoor temperature stabilization and control is the integration of thermal mass with an optimized ventilative cooling profile to enhance the thermal cycle of heat storage. Due to its cyclical behavior, thermal mass effects are difficult to predict and quantify with the traditional steady-state approach to building thermal performance. Dynamic thermal simulations help to assess a building's behavior under transient situations, including the thermal mass influence. However, building codes usually include thermal simulations based on standard assumptions: typical meteorological year (TMY), standard occupancy, standard daily-based lighting and appliances profiles, and standard weekly-based occupancy. Thus, when assumptions change, the actual behavior of the building may vary consistently from the predicted conditions. In this paper, we focused on the ability of thermal mass to contrast the influence of variations from the standard assumptions, especially in relation to climate and ventilation profiles. The results show the necessity of encompassing different risk scenarios when evaluating a free cooling solution performance. Among the different scenarios simulated, natural ventilation misuse shows greater influence on the thermal indoor environment, especially if coupled with low thermal mass.

Potential of Thermal Energy Storage Using Coconut Oil for Air Temperature Control

“…The outdoor night cooling method is only intended for the peak shifting and decreasing of the daytime temperatures. As an alternative method of getting out the TES during the night, some experts use the fan to increase the heat exchange between co_oil and air [12][13][14][15][16]31]. .…”

“…In addition, TES applications have flexibilities in indoor settings for room features (e.g., as room partitions or a drop ceiling, etc.) [12][13][14][15][16].…”

Influence of building design and control parameters on the potential of mixed-mode buildings in India

“…Evidently, mixed-mode buildings have a potential application in Indian climates [47,48,24,49]. Moreover, building design parameters, such as climate and micro-climate [50], building size and geometry [51][52][53], building envelope and construction [51,[54][55][56], internal mass [57][58][59], internal heat gains [60,61], and control parameters for mixed-mode operations [29,15,62,63] determine the potential of mixed-mode buildings. A few of these are also outside the purview of the ECBC.…”

“…Typically, these U-values can only be achieved by applying thermal insulation to external walls. However, this may cause overheating during naturally ventilated periods, leading to thermal discomfort [64,56]. The potential of mixed-mode buildings is determined by their ability to minimise energy consumption during the air-conditioning period, maximise the period of natural ventilation, and provide thermal comfort during both operating modes.…”

Dynamic metrics of natural ventilation cooling effectiveness for interactive modeling

“…For example, two identical buildings in a hot and humid climate could lead to different thermal environments depending on heat capacities of building materials [6]. Thermal mass is known to have significant impact on natural ventilation's cooling potential [7][8][9], and alternating cooling modes, namely mixed-mode, is an effective way to utilize natural ventilation [10][11][12][13]. Window operation controlling the timing of the use of natural ventilation is another significant element in natural ventilation [14][15][16].…”