A new computational tool to assess the integrated ventilation, thermal and energy performance of a seasonal-adaptive double skin façade retrofit for warehouses in the UK
Publication Date
July 29, 2025
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Abstract
The growth of the industrial logistics sector in response to e-commerce demand in the UK has led to a construction boom of increasingly large storage and distribution warehouses yet little is understood about them from a building physics and energy efficiency standpoint. These modern warehouses offer a unique opportunity for the application of façade-based technologies, such as double skin facades, on their expansive envelope.
This thesis presents a new computational tool to assess the integrated ventilation, thermal and energy performance of a seasonal-adaptive double-skin façade retrofit for UK warehouses. Double skin facades are a ventilation technology applied to the interface between indoor and external environments where the energy balance is highly influential on the building’s energy consumption. The novel application of the proposed “seasonal-adaptive” opaque double skin façade to a case study warehouse comprises an aluminium outer skin and warehouse cladding inner skin, separated by a 0.2m air cavity. A level of control over its ventilation and thermal capacity is achieved through percentage closures of the DSF inlet from 25-75% in the direction of both the outer and inner skins.
The computational fluid dynamics tool required a three-step validation process including wind tunnel tests of a 1:50 scale model of the double skin façade warehouse to assess wind performance, climate chamber tests of a 1:1 prototype of the opaque double skin façade to assess buoyancy performance, and lastly, heat mat tests to simulate stratification. Together, in addition to an analytical validation of cross-ventilation in the case study warehouse, this research process ensured a level of validity and reliability. CFD-derived cavity air velocities and temperatures applied to Bernoulli-adapted equations can determine ventilation, and heat gain/removal supplied by the proposed double skin façade system to the warehouse.
The first results chapter assessed the wind-driven ventilation performance of the double skin façade on the warehouse achieving a final error of 7.8% against the experimental data with expected aerodynamic behaviour. A stable vertical cavity airflow rate was observed until it increases at the warehouse inlet height of 9m and promoted cross-ventilation with neutral pressure heights of 4-4.75m in all four seasons in the UK climate. This chapter concluded the double skin façade’s capacity as a natural ventilation technology as it delivered 37ACH at an occupant level of 2m. These results suggest that a modernisation of warehouse ventilation design guidelines is required.
The second results chapter evaluated the buoyancy-driven ventilation and thermal performance of the double skin façade at prototype and full-scale dimensions. Winter conditions (300W/m2 and -4oC) produced the highest thermal gradients in the prototype cavity of 13oC/m suggesting a high thermal potential in colder climates or seasons. For cavity air velocity and temperature from CFD, errors of 16% and 27% were obtained against existing literature, whilst 12% and 3.5% were achieved versus the climate chamber data. Flow rates of 1000-6100L/s and 27kW, 10kW and -5kW of pre-heating or “cooling” are produced in winter, intermediate and summer conditions. The double skin façade retrofit also reduced the U-value of the original warehouse cladding to 0.19-0.27W/m2K from 0.31W/m2K.
The stand-alone chapter excluded the double skin façade to instead focus on vertical heating at 1:50 and full-scale in the case study warehouse. Storage racking increased the thermal gradient of the empty small-scale warehouse by 23%, a significant impact on stratification. The analytically predicted Grashof number at full-scale from temperature data in the empty small- scale warehouse is an overestimation of 4.8x1011 compared 4.5x109 obtained in CFD. Applying cross- ventilation openings reduced stratification in the presence of 40W/m2 floor area heat gains, and storage racking presents issues for controlling internal airflow and thermal patterns.
The integrated computational tool, presented in the final chapter, assesses the double skin façade warehouse performance in combined wind and buoyancy conditions. Cross-ventilation in the warehouse was analytically validated with an error of 23%. Wind conditions representative of the four seasons applied under an irradiance of 300W/m2 produced significant pre-heating of 12.6oC (winter) and 21-23oC (intermediate) with minimal summer heating of 1.8oC. A total warehouse inlet opening area of 3.75m3 provides 2-3 times the ventilation requirements, and the DSF inlet area could reduce from 7.2m2 to 0.95-1.4m2. Different DSF inlet configurations were optimised for the warehouse inlet openings. The fully open DSF (36m x 9m) can deliver 0.59MW, 0.50MW, 18kW and 0.45MW in winter, spring, summer and autumn at 2% of the warehouse construction cost, and a payback period of under a year.
At a minimum, this thesis closes knowledge gaps in the performance of opaque double skin façades, the viability of DSF retrofits for warehouses, and the experimental methods to validate CFD models simulating air and thermal phenomena occurring in warehouses. However, it also challenges existing regulatory, industrial and academic understanding of a largely overlooked building type in building physics research and low-energy building technology application
Item Type
ethesis
Thesis Type
PhD
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FINAL VERSION Kate Pelletier 14301728 PhD Thesis.pdf
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