Park View Community School in Manchester is one of the most energy efficient designs in the UK with no cost penalty compared to conventional schools. Brian Morris reveals the secret
As with any building, schools must meet stringent carbon emission standards. For Park View Community School, Manchester City Council wanted to beat the then Part L (2006) carbon emissions target by a further 25 per cent, and then 20 per cent on site renewables.
BCM was awarded the contract on the basis that we could meet all the criteria at no extra cost over a conventional school building. The way we could demonstrate this was through Dynamic Simulation Modelling (DSM). In my opinion, no m&e consultant should go into detailed design without first employing DSM. It provides so much information on various scenarios and can pinpoint the most efficient and cost effective solutions. All these scenarios can be evaluated for capital and lifetime costs and the whole package shared with the team in a professional and accurate manner putting carbon emissions top of the agenda but also allowing opinions and ideas from others in the team to be evaluated.
The most important design criteria for schools is BB101 (Building Bulletin 101 - Ventilation of School Buildings) which requires compliance with two out of the following three criteria:
- Internal temperature when the space is occupied should not exceed 32 deg C.
- Internal temperature should not be greater than 5 deg C above external ambient in summer.
- Internal temperature should not exceed 28 deg C for more than 120 hours.
At BCM we use DSM, employing Tas software to inform our designs strategy and model different scenarios to determine the optimum solution for a particular project. Each scenario incorporates different combinations of fabric/ 'U' values, glazing solutions, heating solutions, lighting control scenarios and ventilation strategies.
These option appraisals are discussed in detail with the team early in the project to determine the scheme which is the most cost effective (in terms of capital and/or revenue costs) to meet the particular requirements. Figure 1 shows most of these scenarios and how they impact on the total carbon emissions.
Look at the carbon emissions for the standard design and then see how the carbon emissions are portrayed with successive reductions for various options. This simple bar chart illustrates the areas that need to be addressed to meet the target carbon emissions. If each of these elements are then costed, both capital and lifetime, a carbon emission and cost implication matrix can be established. For Park View, there was a specific target for carbon emissions and a target for cost which meant that the building would not exceed the cost for a conventional school with regard to carbon emissions. Everything to the left of the MCC target in Figure 1 was an improvement on what the client required and therefore consideration could be given to these options and cost implications.
A critical design factor is to optimise the daylight, but, at the same time, minimise the solar gain to a classroom. It is important to increase daylighting to enable reduction of artificial lighting, but not at the expense of admitting too much solar gain, which could result in the design failing to meet BB101 temperature criteria. Therefore, we have used Tas to determine the best glazing solution for the particular elevation.
Figure 2 provides an overview in the form of a bar chart of the carbon emissions of the actual design which was ultimately selected.
As a result of this process, Park View achieved an EPC rating of A23 (top 0.1 per cent primary school in the country) within traditional capital cost parameters. The benefit of this will be a lower carbon footprint and lower running costs.
This process allowed the construction team to design the project secure in the knowledge that the building could achieve an A rated EPC and that the solution was within budget.
DSM is a powerful design tool. On this project, we were able to deliver a school with energy efficiency credentials that put it into the top 20 primary schools in the UK.
// The author is managing director of BCM //