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Amid recent concern about overheating in Passivhaus, this study investigates geometrical implication of façade design to alleviate overheating in new build energy-efficient homes in the UK. The study proposes self-shading façade design as a less conventional approach to passively protecting the house from the excessive solar gain in summer. The findings show that implementing an optimum angle slanted wall can moderate indoor temperature variations between day and night in summer and could potentially act as an effective shading device. The suggested tilted façade is compared alongside other conventional approaches, such as overhangs and reduced WWR, to compare their relative effectiveness in reducing overheating risk.

Residents of the dense urban environment in Hong Kong suffer from poor living conditions due to building overheating, especially during near-extreme summer conditions. In this study, the thermal comfort and energy performance of typical public rental housing (PRH) building types were simulated using DesignBuilder. Results show that the oldest Slab type PRH, which has a compact building form, has the highest indoor air temperature, yet the lowest cooling energy demand. On the other hand, the Trident type PRH, with the largest external wall U-value, performs the worst overall and is the most responsive to outdoor temperature changes.

© 2017 Elsevier B.V. Building performance evaluation is crucial for sustainable urban developments. In high-density cities, occupants suffer from poor living conditions due to building overheating, especially during increasingly frequent near-extreme summer conditions caused by climate change. To represent this situation, the summer reference year weather data was employed for building simulations using DesignBuilder. This study aims to evaluate the thermal comfort and energy consumption of four typical public rental housing (PRH) building types in Hong Kong. For free-running flats, results show generally higher air temperatures in the oldest PRH type (Slab) with a compact linear building form and the most sensitive response to outdoor temperature changes for another older PRH type (Trident) with a Y-shaped design, possibly owing to its high wall conductivity. Occupants in all building types experience a ???10% increase in the proportion of discomfort hours when compared to results for typical summer conditions, but overheating is the most severe in Slab type PRH. Following an initial assessment of the cooling energy usage, a simple sensitivity test was conducted to explore the potential energy savings by various passive design strategies, including shading and reducing the exposed cooled space. A cross-shaped building form also appears to be more energy efficient. These findings, complemented by further parametric analyses, may prove useful when designing buildings for climate change.

This study investigated the potential negative impacts of future UK climate change on dwellings. In particular, the risk of overheating was considered for a Passivhaus dwelling in London. The study used dynamic simulation modelling software to investigate the potential use of building geometry to control current and future overheating risks in the dwelling for London climate. Specifically, the focus was on the optimum inclination of a south facade to make use of the building's shape to self- protect itself. A range of different inclined facades were examined to test their effectiveness in reducing the overheating risk. The research found that implementing a 115° tilted facade could completely eliminate the risk of overheating in current climate, but with some consequence for natural ventilation and daylighting. Future overheating was significantly reduced by the tilted facade. However, geometric considerations could not eradicate completely the risk of overheating particularly by the 2080s. The study also used CFD modelling and sensitivity analysis to investigate the effect of the facade geometry on the wind pressure distributions on and around the building surface. This was done to assess natural ventilation flows for alternative facade inclinations.

Buildings can be designed to require far less energy than today's average. Reducing energy consumption of buildings in hot-dry climates by using natural energy sources to provide comfortable microclimate is the main concern of this study. In this paper design strategies in terms of energy efficiency have been considered based on proper building form, material selection and orientation and by taking advantages of passive cooling strategies and ventilation. The study aims to show that the idea of using natural energy and passive cooling strategies came from the vernacular principles.

The Passivhaus strategy employs super insulation to reduce the heat transfer through the building envelope. It has been argued that super insulated homes are vulnerable to summer overheating risks, even in the current climate. The UK is expected to experience hotter and more extreme summers in the coming decades and the risk of buildings overheating may become very significant in future climate scenarios. The Passivhaus approach can use much of the solar energy from its relatively large glazing in south facade but this large glazing may eventually lead to overheating in summer time. The study used parametric design modelling to generate differently inclined facade geometries for south elevations. Each elevation was then simulated by means of dynamic building simulation software in order to examine to what extend inclined wall mitigate summer overheating risk for Passivhaus dwellings in the UK under alternative future weather projections.