Regulations

Yes, the inclusion of natural ventilation alone will directly help you gain 1 BREEAM point. However you can gain many more points indirectly from natural ventilation.

Here are just some of the hidden benefits of natural ventilation:

• A building designed to incorporate a natural ventilation strategy will typically be more energy efficient so there will be CO2 savings.
• Naturally ventilated buildings tend to be shallower plan, as you need a certain proximity to windows/openings, so the building will tend to have better day lighting and lower lighting requirements.

• The building can use free cooling and reduce the use of refrigerants

These are some of the areas where additional BREAM points can be obtained:

• Day lighting
• View out
• Reduction in CO2 emissions
• Free cooling
• Indoor air quality
• Thermal comfort
• Thermal zoning
• Refrigerant GWP - building Services

Yes. A well controlled naturally ventilated building can meet BB101 whether that is to provide occupants with fresh air or to minimise overheating in the summer.

BB101 is the regulation for ventilating school buildings. Much of the concern around natural ventilation arises when it is cold outside and people shut off the system to avoid cold draughts, obviously our unique, natural mixing ventilation strategy avoids this problem.

Table 1.1 in BB93 gives performance standards on the maximum ambient noise levels inside teaching spaces. Natural ventilation systems must ensure that when providing minimum ventilation (at 3l/s/person) those levels are not exceeded either from noise ingress from the outside, or noise generated from the equipment itself.

BB101 (use in conjunction with BB93) states that when providing ventilation at 8l/s/person through natural means, noise levels may be increased by 5 dB LAeq,30min. Also stated in BB101, at the discretion of the teacher, when the classroom is occupied higher noise levels may be acceptable when higher rates of ventilation than 8l/s per person are required for example during overheating on hot summer days when it may be necessary to open all the windows.

The system is sized to meet minimum average ventilation rates of 3l/s/person in winter. The system does this by monitoring to CO2 levels in the room and feeding the signals back to our controller which in turn alters the damper position to admit the correct amount of fresh air into the room. The temperature of the incoming air is also measured to ensure that the fans run at a suitable speed to achieve the correct mixing ratios with internal classroom air.

The system minimises heating energy consumption because no preheating is applied to the incoming air, because it enters as a mixed airstream at high level.

Breathing Buildings carry out their own thermal modelling of spaces taking into account solar gain all other casual gains in the space, and using the closest CIBSE test reference year (TRY) weather file to predict summertime temperatures and ensure sufficient ventilation area is provided to prevent summertime overheating in accordance with BB101.

The dampers which are integral to our R, S and F-series units have been tested for air leakage. The high performance variable control dampers provide air leakage at 25% lower levels than current building regulations of 10m3/hr/m2.