Façade Design Effect on Passive Ventilation of Buildings

Description

Façade Design Effect on Passive Ventilation of a Building, Industrial Application

Introduction

One side of a building structure, which is often in direct contact with the ambient environment, is known as the façade (see Fig.1). Nowadays, facade design’s effect on the passive ventilation of buildings is one of the major fields of interest for architectural and energy engineering.

Despite the fact that it gives the building a distinctive appearance, it is one of the most crucial components of the overall design of the building from an energy aspect. A building’s façade may take on a variety of shapes and sizes, leading to various thermal comfort and energy consumption.

In fact, it is one of those elements of the building that gives engineers the freedom to provide part of the needed energy using Passive ventilation systems.

Project Description of Façade Design Effect on Passive Ventilation

In this project, a three-floor apartment located in the capital city of the New South Wales state, Sydney, is simulated. This study investigates different façade conditions to reach the best-case scenario, ensuring natural ventilation, best thermal condition and air change per hour (ACH).

The first step gathers general information to estimate the geographical and thermal conditions. Sydney, with 151.20 longitude and -33.865 latitude coordinates, experiences the coldest weather condition in July & August, with an average temperature of 283K. Additionally, the building got 3 floors with an 80 m^2 cross-section area and 2.8m height.

The client also set a limitation and asked for glass as façades material. As mentioned, the two prior design targets are to provide part of the energy need of the building and natural ventilation measured by the ACH parameter. Therefore, our experts came up with 3 different facade designs predicted to satisfy the targets.

Case 1 is dedicated to the façade extended fully to cover the building’s front view. Plus, it got a separate inlet and outlet vent. A schematic of each case design is depicted. Note that the outlets and inlets are colored in red and blue colors.

case 1:

In case 2, the inlet and outlet vents are installed on a modified façade. In this case, the façade is established from three separate parts, each for a different floor and not in contact with each other.

case 2: 

In the third case, we extended the facade like in the first case, but one inlet and outlet are implemented.

case 3:

Figure 2- a) case 1 b) case 2 with separate façade parts c) case 3 with one inlet and outlet

Analysis of Façade Design Effect on Passive Ventilation

After the simulation, we gathered the results in the table below.

As can be seen, the temperature distribution is uniform in cases 1&2, while there is a distinct difference between the three floors of case 3. It is also visible in the temperature volume rendering of case 3 depicted in figure 3c.

case 1: case 2: case 3:

Figure 3- Temperature distribution in three floors of a) case 1 b) case 2 c) case 3

Hence, from the aspect of energy, we need to determine the building’s average temperature, which is 289.58K, 289.3K, and 290.15K for cases 1 to 3, respectively.

On the other side, the façade geometrical design and vents arrangements give us different ventilation conditions. Based on the reported data and streamline contour (Fig 4), the reduction in vents numbers successfully trapped the hot air in the façade zone. It plays a pivotal role as an insulation layer toward cold ambient air.

To conclude, the design of case 3 leads to the best thermal and ventilation condition and can fulfill the targets compared to the other designs.

It should be reminded that the purpose of using passive ventilation systems is just to benefit from their effects. So, it cannot satisfy the living conditions. Thus, we neglect the inappropriate thermal condition of the first floor.