New Approved Document O
In December 2021, the government announced changes to the building regulations in a step towards net zero carbon in 2050. These changes take effect in June 2022, leaving developers with new challenges which quickly need to be resolved. One of the biggest changes includes the introduction of a new approved document, to outline the standards for removing excess heat from a building. This is necessary, as the climate is getting hotter and buildings are becoming more insulated to reduce energy consumption. So overheating, particularly in the summer, is becoming a serious health problem.
How Will Buildings Have to Change?
The new approved document outlines two main requirements:
- Limit solar heat gains and provide means to extract excess heat.
- Ensure new measures account for safety and enjoyment of the residence.
These requirements also specify that mechanical cooling solutions should only be used where passive cooling means cannot remove sufficient heat. Proof should be provided that all passive cooling solutions have been considered before mechanical solutions can be used. This means that natural residential ventilation solutions will be necessary for all buildings covered by this new document.
The requirement for removing excess heat is dependent on the building design. The approved document details how this can be specified using dynamic thermal modelling or a simplified method. The simplified method requires the free area of the ventilation to be a percentage of either 4-13% of the room floor area or 55-95% of the glazing area. The exact percentage depends on the risk factor for the building. The dynamic thermal modelling is more precise for the specific building and involves simulating the conditions of the room and when heat extraction may be necessary, this is based on the TM59 document.
The cooling solution must ensure the safety and enjoyment of the residence, this includes low noise levels, security, and protection from falling. One of the biggest challenges is maintaining low noise levels when introducing passive cooling. Opening a window, for example, may extract excess heat but will also allow noise into the building. The new approved document states that windows may not be used for this purpose if the resulting noise is 40dB LAeq,8hrs, roughly the same level as a quiet library. This new challenge requires innovative solutions to allow the removal of excess heat from indoors while restricting noise from outdoors.
How Do TEK Solutions Overcome These New Challenges?
TEK natural ventilation solutions have already been utilized across the UK to remove excess heat from residential buildings in very noisy areas. Particularly in urban areas, where opening a window to remove heat would be too noisy and uncomfortable.
The main challenge is to maintain a large free area while providing a high noise reduction. Traditional acoustic ventilation such as window trickle vents often have very low free areas to achieve good acoustic performance. TEK solutions provide extremely high noise attenuation while achieving superior airflow. The free area of TEK ventilation can be balanced with the acoustic performance to meet the specific project needs. TEK ensure that internal noise levels are met in each room while also providing background and overheating ventilation with very low energy consumption. This overcomes all of the design problems introduced by these regulation changes and ensures new buildings are comfortable and safe, with a low carbon footprint