Modern buildings are grappling with a growing issue – heightened temperatures. As global temperatures rise, the impact on our homes and workplaces becomes increasingly evident. This concern extends beyond mere comfort; it demands a strategic and safe approach to building design and occupancy. Gain a comprehensive understanding of the root causes and viable remedies as we explore the pressing matter of building overheating and the measures to mitigate it.
The pressing issue of climate change
The UK’s increasingly warm summers, exacerbated by the heatwaves experienced in recent seasons, underscore the pressing issue of climate change. With the UK’s ambitious target for a net-zero carbon footprint by 2050, the problem of building overheating is of utmost relevance. Effective temperature control in buildings holds promise for improving energy efficiency and will become increasingly significant for the well-being and comfort of its occupants.
Why are buildings overheating?
There are several reasons why modern buildings are prone to overheating:
- Increased insulation: Modern buildings prioritise heavy insulation to conserve heat, aligning with design standards like Passivhaus. While this is advantageous for retaining warmth during colder seasons, it can inadvertently trap heat in the summer months.
- Lack of natural ventilation: Many modern structures, especially high-rise buildings, may rely on inadequate measures for sufficient natural ventilation. In some cases, windows are not designed to be operable, further trapping the heat.
- Urban heat island effect: Urban environments, with their dense concentrations of buildings and asphalt, tend to retain more heat, resulting in higher temperatures than less built-up areas.
- Internal sources: From cooking to using electronic devices, everyday activities generate heat, contributing to climbing indoor temperatures.
- Lack of right design for sun exposure: Often, buildings overheat due to unsuitable designs for sun exposure, like having excessive glazed openings facing south without adequate sun screening. A sound strategy for sun shading and orientation consideration is essential to prevent this solar gain, especially during peak hours.
The dangers of overheating in buildings
CIBSE, the Chartered Institution of Building Services Engineers, frames overheating as the condition where the threshold of 28°C, considered comfortable, is exceeded for more than 1% of the time. The challenge isn’t solely about discomfort.
Overheating is associated with adverse effects on productivity, well-being, and health. Alarmingly, there is a significant risk of heat stress if internal temperatures rise above 35°C. The implications of neglecting this issue could be severe, with some projections estimating up to 4,500 premature deaths per year by 2050 in the UK due to overheating in buildings. Yet, it is no all doom and gloom and the UK is taking steps to overcome the challenge of rising temperatures in the estate industry.
How to avoid overheating in buildings?
The UK’s Heat and Buildings Strategy has laid the foundation for a comprehensive approach to creating buildings that prioritise both energy efficiency and the well-being and safety of occupants. The recently introduced building regulations emphasise reducing overheating risks in new homes.
Maximising the potential for natural ventilation is crucial in curbing overheating and keeping a comfortable indoor environment. In addition, carefully consider other measures, including the deliberate use of building materials with favourable thermal properties, the implementation of adequate insulation and airtightness strategies, the use of external shading, the optimisation of outdoor spaces, and the establishment of proper cross ventilation. These elements collectively work to prevent and alleviate overheating in buildings.
Mitigating solar gains
One fundamental approach to prevent overheating is to manage temperature increases caused by solar radiation; this can be effectively achieved through several means, including:
- Installing fixed shading devices, such as shutters and blinds
- Thoughtful glazing designing, factoring in size and orientation
- Incorporating building design elements, such as the strategic placement of balconies
- Leveraging shading provided by neighbouring permanent structures.
Removing excess heat
Despite effectively managing solar gains, buildings can still experience overheating. To address and remove excess heat, these are some typical strategies:
- Promoting natural ventilation in the design, which may involve including operating windows or incorporating ventilation louvres
- Implementing mechanical ventilation systems
- Employing mechanical cooling systems, such as air conditioning.
In alignment with the ongoing efforts to mitigate climate change, passive solutions –those not requiring energy consumption– should be prioritised. However, this is a multilevel challenge. While environmentally friendly, natural ventilation may prove inadequate during exceptionally hot spells. Furthermore, in urban settings, opening windows could introduce pollutants, potentially jeopardising indoor air quality and overall comfort.
The balance between cooling and air quality
Maintaining superior indoor air quality is as vital as ensuring comfortable temperatures. Recent updates to building regulations, including Part F, underscore the significance of preserving or even improving ventilation during building renovations or extensions. A noteworthy recommendation suggests fitting replacement windows with trickle vents, unless a suitable alternative ventilation system is already in place.
To prevent overheating issues in buildings, consider and address this matter in collaboration with your designer and relevant consultants during the design phase of constructing a new building or extension. This long-sighted approach will help pinpoint potential overheating risks and devise effective strategies to mitigate them.
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Understanding approved document Part O of Building Regulations
In June 2022, the Building Regulations introduced updates with approved document Part O, focusing on the issue of overheating in buildings.
The concept of ‘overheating’ within this context is tackled through two main strategies:
- Prevention: This involves managing the direct sunlight allowed to enter through windows and other glazed areas, attending to factors such as the façade orientation.
- Remedy: This ensures a way to quickly expel any excess heat from rooms when temperatures start to climb is in place.
Another significant concern addressed in Part O is the accumulation of unwanted heat due to poorly managed heating systems; this is a typical scenario in apartment complexes where heating pipes run between floors and share a communal heating source.
Compliance with Part O regulations requires carefully considering specific factors to determine the right size of windows and glazed regions. These aspects include:
- The overall floor space of the room in question
- The orientation of the windows, whether they’re facing south, north, east, or west
- The existence of cross-ventilation in the structure, such as having windows on opposing walls that can be opened to facilitate airflow
- The building’s location, along with the associated risk level –notably, certain London postcodes have been classified as having the highest risk.
For those buildings situated in high-risk zones, it will be mandatory to incorporate external shading solutions.
Determining what counts specifically as ‘overheating’ under Part O concerns two assessment methods:
- The Simplified Method. In broad terms, to determine the overheating risk strategy based on the building’s location and cross-ventilation. However, it is not suitable for all structures.
- Dynamic Thermal Modelling. Used to predict any building’s internal conditions and energy requirements at frequent intervals via weather data and the building’s specific characteristics.
It is essential to highlight that Approved Document Part O’s guidelines are strictly for new domestic constructions. If you are adding extensions or conservatories to an existing property, these are exempt from Part O stipulations. Similarly, if you’re replacing windows or adding conservatories to existing residential properties, Part O does not affect these modifications.
Overheating in buildings: Wrapping up
As the global challenge of climate change persists, the emphasis on addressing building overheating carries significant weight in the property sector. By understanding its underlying causes and seeking innovative solutions, we aim to shape cities that are both habitable and kind to the planet.
At WindsorPatania, we prioritise the comfort and safety of those inside buildings. Balancing cutting-edge designs with sustainable approaches is at the core of our ethos. To incorporate sustainable methods into your projects, explore our sustainability services. If you are interested in upgrading existing residential spaces, take advantage of our residential retrofit services. We are committed to fostering a greener future, one building at a time.