Providing a better learning environment
The ambitious BSF programme will see almost every school in England rebuilt or refurbished in the next 15 years. This investment is underpinned by Building Bulletin 101 which provides the regulatory framework in support of the Building Regulations for the adequate provision of ventilation in schools. It deals with the design of school buildings to meet the ventilation requirements of both The School Premises Regulations and the Building Regulations Part F (Ventilation).
The challenge is to create a healthy learning environment, facilitated by excellent indoor air quality where problems with moisture, CO2 and external fumes are eliminated.
Building Bulletin 101 specifies limiting CO2 levels within teaching and learning spaces to 1500 parts per million. However, fresh air supply rates per person in schools are often so low that CO2 levels are well above this recommended level, leading to adverse health effects and also impacting on the learning performance of pupils.
Recent research by the Office of the Deputy Prime Minister found that 50% of the ventilation rates measured in eight English schools came below the minimum recommended levels. Poor indoor air quality also puts pupils and staff at an increased risk from health problems, such as fatigue, nausea and asthma. In fact, in a study carried out by the San Francisco Health Department, two pilot schools saw a 50% drop in student use of asthma inhalers following indoor air quality improvements. This is especially significant when asthma-related illness is one of the most common causes of school absences in the UK.
Meanwhile, during a European study in the late 1990s, 800 students completed health symptom questionnaires while a computer-based programme scored their ability to concentrate and at the same time measured CO2 levels in the classrooms. The study found that high CO2 levels were strongly related to student health symptoms and performance. This research is further supported by the Technical University of Denmark who in 2005 found that by improving classroom ventilation in a Danish school the performance of school work by children could be substantially improved.
Indoor air quality
On-demand ventilation is the answer to improving indoor air quality in schools. With traditional fixed volume ventilation the system is either on or off irrespective of the number of people in the room. In this type of environment, you run the risk of creating a mediocre and unproductive classroom environment through over or under ventilation with a resulting waste of energy.
Instead, demand ventilation works by responding to the exact ventilation demands of a room at any one time, supplying or extracting air only when and to the level it is required. The system is activated according to sophisticated control and sensing options. A range of sensors, such as CO2, PIR occupancy detection, humidity or temperature, are employed to determine the precise number of people in a classroom at any one time, and manage the system’s ventilation rates accordingly. They communicate with the main unit which, in turn, drives the fan to the required speed to deliver the airflow and respond exactly to classroom conditions. Sensors can be combined to generate a hierarchy of control for the ventilation system and ventilation system operation can also be easily linked in to a Building Management System for full control and monitoring, if required. Therefore, only the energy that is needed to ventilate is actually used. It is the perfect answer to key questions such as ‘Why ventilate a classroom you’re not using?’ or ‘Why over-ventilate a room with only 15 students and not 30 inside?’.
At Vent-Axia, we also recognise the benefits of integrating heat recovery into the ventilation strategy. The latest on-demand ventilation systems, such as, Sentinel Totus D-ERV provide especially impressive energy savings because they integrate 90% energy recovery into the ventilation system. This type of system extracts the energy from the warm, stale air taken from classroom areas before it is exhausted to outside whilst fresh, incoming air is preheated via the high efficiency plate heat exchanger and supplied into the classroom. The energy recovery process is proven to utilise up to 90% of the heat which in winter would otherwise be wasted to outside. The result is a further boost to the energy performance credentials of the ventilation system especially in larger school buildings.
This type of system also offers schools further energy saving potential. An automatic summer bypass will take advantage of any free cooling available when the ambient temperature is below the room design condition, something found particularly during the spring and autumn seasons. The TOTUS system also incorporates interlocks for associated heating and cooling equipment installed to optimise energy recovery potential and eliminate any possibilities of systems conflict. There is an installer settable night-time purge facility which will purge the room overnight in the summer to reduce start up temperature/loads for associated cooling systems and help reduce over heat in summer from non air conditioned spaces.
Incorporating an on-demand system also cuts out the outside noise distractions, heat losses and other pollutants that typically come with opening windows. Since the system is automatically controlled, it also eliminates the need for manual operation by teachers. At the same time, it improves comfort, keeping CO2 levels within prescribed regulatory limits for school classrooms, as defined by Building Bulletin 101.
At a time when many schools are having to cope with the effects of spiralling fuel costs – some estimates point to increases of £50,000 in the past 18 months – on-demand ventilation can bring significant advantages. And by saving energy, schools will not only be able to reduce their environmental impact but can also cut their utility costs, allowing money to be directed to other school activities.