School Performance Specifications. SPACES Engineering Technical Meeting 22 September 2015

Transcription

1 School Performance Specifications SPACES Engineering Technical Meeting 22 September 2015

2 EFA Facilities Output Specification: Introduced in 2013 to promote: well-integrated and simple buildings that benefit from daylight and hybrid ventilation Buildings where the fabric is the primary means of controlling the internal environment Buildings that perform better than ones with complex M&E systems and bolt-on technological features

3 Baseline designs Demonstrate one way that area within cost an be achieved Baseline designs demonstrate ways to meet the EFA Output Specifications Demonstrate how a wide range of school-specific requirements can be accommodated Will match typical Schedules of Accommodation for a range of school sizes

4 Specifications and Baseline Designs Show possible ways to get daylight into circulation areas and rear of classrooms Contractors have developed these further to produce their own standard solutions Single storey Primary typical sections

5 Standardised Approach We are looking for: Standardised approaches to plant and services, eg strategy for routing services, risers, service cores, etc Standardised solutions for the façade, ventilation systems, acoustics and lighting.

6 Standardisation: entrance and admin 1. Draught lobby 2. Public access to reception, interview room and toilet only 3. Open reception desk 4. Pupil reception from secure side 5. Sick room and toilet 6. Facilities available to community without access to main school General office sick room int recep wc Visitor entrance acc wc

7 Standardisation: performing arts Movable bleacher seating rather than sliding/folding screen Central access from dining/foyer space Flexible performing area control room at back Drama space accessible from performance area as back stage facility

8 And standard components

9 Area Data Sheets Area Data Sheets for every generic type of room Specifies dimensions, doorset, finishes, acoustic and environmental requirements Linked to a generic layout of furniture & equipment Identifies use of legacy items

10 Design priorities Provide daylight into circulation areas and rear of classrooms Meet the new adaptive thermal comfort criteria to avoid summertime overheating Meet carbon dioxide concentration criteria to provide adequate indoor air quality in classrooms Is indoor environment easily controllable locally by building users?

11 Daylight: what s the issue? Daylight is essential to prevent the development of short sight in children. Recent research suggests that children should spend at least 3 hours in high levels of daylight, preferably outside, every day. With good daylighting, the lighting energy use over a year can be reduced by 40%. High levels of daylight must be controlled to avoid disability glare to allow children to see their work clearly.

12 Daylight: what can go wrong? Daylight factor design can lead to too much glass at the perimeter, which can cause glare and overheating, especially if uniformity is not achieved. Dark gloomy internal spaces can be devoid of daylight Halls with minimal daylight Blinds that can conflict with opening of windows Suspended ceilings, high cills and downstand beams can reduce daylight

13 Daylight design Balanced daylight is best there is a benefit from using twosides/directions where possible light shelves, light wells and light slots, Rooflights and clerestories can provide good daylight quality. Halls must be well daylit. Acoustic panels in classrooms should not block the daylight nor restrict the distribution of daylight to the rear of the room Carpet and floor reflectance should be as high as practicable Where do we want carpets in schools? Rugs to an area of rooms may be better than carpets.

14 Electrically operated roller blinds on rooflights in the hall of a PSBP School Bottom bar is encapsulated into brushed lined blind side channels. Operation by wall mounted switch motorised electronic control.

15 Acoustics and noise control Acoustics standards to BB edition. Guidance to be published soon by IoA/ANC on how to achieve compliance with BB

16 Acoustics and noise control Key points Limits on noise from new equipment such as data projectors, and contractor required to advise how to improve performance of legacy equipment. Maximum sound levels specified for window or ventilator actuators. Hearing Impaired pupils usually have radio aids and do not use induction loops so audio visual equipment, eg in halls and classrooms, should be compatible with radio aids. Any open plan or semi open plan teaching areas must have a full Speech Transmission Calculation carried out.

17 Ventilation Fresh air is critical for learning, health and hygiene The CO 2 levels required of 1000ppm-1500ppm in classrooms can be exceeded within 20 minutes of the start of a lesson. What can go wrong? Levels in poorly ventilated classrooms of over 2500ppm throughout the day are common in schools. At these levels concentration fades. Openable areas too small and single sided ventilation does not provide adequate ventilation in summertime mode Lack of user/management control Challenges Does the ventilation solution work under all weather conditions and is it robust, simple to operate and maintain, and is it energy efficient?

18 Ventilation standards AD F ASHRAE 62-1 will be revised soon EN gives standards for filtration of outside air CIBSE AM10 will also be revised soon IGEM UP11 Gas safety in educational buildings is being now to coincide with the BB101 revision European guidelines on air quality need to be considered There are other standards too that might be useful Is there a role for BSI in aligning standards?

19 Key points Ventilation Cold draughts in wintertime Window and ventilation design needs to allow large volume flow for summertime ventilation and prevent dumping of cold air onto occupants during winter Blinds and restrictors Windows, vents and blinds need to be robust, easy to operate and supply the necessary air: Window ventilation openings should not be obstructed by blinds or curtains when these are opened Blinds should not cut off all daylight and views out Where dim-out blinds are required, they should provide a suitable daylight illuminance in the space and should not restrict ventilation

20 Common design issues thermal comfort in cold weather In the 1960 s, classroom radiators were 160W/m 2, under steel windows that provided reasonable ventilation levels when closed because they were leaky. The diffused ventilation air was warmed by the big radiators. Very few problems with cold incoming air Now classroom radiators are circa. 60W/m 2, insufficient heat to temper incoming ventilation air via windows in cold weather. The result is that (CFD modelling and practice) occupants have air <15ºC around them. They are cold. Occupant behaviour is to close the windows, and the CO 2 goes too high

21 CFD thermal comfort in cold weather. Discomfort from introducing outside air at high level

22 Line Plume Calculator The tool asks for several simple inputs: Dimensions of the room Type of inlet (window / damper) Occupancy Flow rates Distance to reach fully turbulent flow 0 m Width of opening window/damper 4 m Average temperature of classroom 21 C Height from floor to ceiling 3 m Vertical height of opening high level window/damper 0.5 m High level opening type Top hung window Number of occupants 32 Minimum fresh air rate per person 5 l/s

23 Design issues in hot weather Ventilation close to ceiling level is effective for cooling the slab

24 Thermal comfort: what s the issue? High temperatures affect student performance What can go wrong? Design to fixed temperature limits in BB101 e.g. max C is inadequate for mechanical and hybrid systems. FOS now requires design to CIBSE TM 52/European Standard EN Adaptive thermal comfort criteria High solar gain due to too much glass Lack of thermal mass and less openable area than needed for summertime ventilation Ineffectiveness of single sided ventilation for summertime ventilation.

25 Thermal comfort standards Workplace Regulations on Ventilation and Temperature PD CR 1752: 1999 Ventilation for buildings Design criteria for the indoor environment BS EN ISO 7730: 2005 Ergonomics of the thermal environment (PMV and PPD indices) local comfort criteria EN for adaptive thermal comfort is being revised and will supersede what is CIBSE TM52 ASHRAE 55 EFA cold draft criterion There are other standards too that might be useful Is there a role for BSI in aligning standards?

26 Thermal comfort comparison

27 Key points thermal comfort Mechanical cooling should not be provided to classrooms and teaching spaces and minimised elsewhere, e.g. in server rooms. We are not designing for legacy equipment but for the loads specified in the FOS of 25W/m 2 for practical spaces and IT rooms and 15 W/m 2 for general teaching spaces. Where legacy loads are higher the performance in use criteria for overheating do not apply. Criterion 2 is currently a problem as designs usually fail. BB101 revision advisory group is looking at how to deal with this. An option is to revise the criterion to make it a weekly weighted average rather than a daily weighted average. This will resolve the effect of one hot day making the design fail in some locations.

28 Thermal comfort Classrooms have high internal gains 30 pupils at 80W each in a 60m 2 classroom is 40W/m 2. Add some equipment and the total quickly gets to 50W/m 2 If design day heating is 60W/m 2, internal gains provide all the heat that is needed until the outside air temperature is <5ºC. How many school days are colder than 5ºC each year? Around 30? So heating energy in occupied hours is only needed 30 days/year. If your heating boilers are going to be hot for 200+ days/year that will waste a lot of energy.

29 Underfloor heating Underfloor heating can cause overheating. Under-floor heating with surface temperatures above 23ºC can seriously over-heat a room. Floor emitter slope is 11W/m 2 per ºC. A floor at 27ºC will give >60W/m 2. When a class (40W/m 2 ) walks in, it will get so hot that the windows will be opened to dump paid-for heating energy. Screeded underfloor heating has a thermal time constant far longer than a working day. If you turn the heating off at 9am, the floor is still hot at 4pm A lot of energy can be wasted because the emitter response is too slow.

30 Temperature C C Whitecross School constructed in Typical Classroom Temperature 23.5 C 26.5 C Concrete ceilings and timber-frame external walls Outside Air Temperature Typical classroom held at 26.5 C when outside temperature 33 C :00 06:00 12:00 18:00 00:00 Typical School Day Output from BMS 15 th July 2006 English Classroom 6 High mass structure and the high levels of thermal insulation mean building damps down the internal temperature variations

31 2015 UK school designs Room based ventilation systems with CO 2 and temperature control. Assisted natural mixing ventilation or mechanical ventilation with heat recover Daylight design using Climate Based Daylight Modelling Exposed thermal mass in ceilings Acoustic absorbers - Hanging absorbers or - wings to light fittings or as - as part of radiant panels

32 Classroom based assisted mixing ventilation system

33 Natural Mode Natural mode: Damper opens, single sided ventilation, works with other openings in space. In peak summertime fan assistance increases cooling [Diagrams:

34 Summer boost Summer boost: Damper opens fully, air delivered to rear of space; natural exhaust through unit; night cooling

35 Winter operation In winter assisted mixing prevents cold drafts; mixes warm room air with fresh external air; natural exhaust through unit

36

37 Classroom based control system

38 Classroom based mechanical ventilation system with heat recovery

39

40 Wintertime ventilation

41 Mid-season ventilation

42 Summertime Ventilation

43 Radiant panels Radiant panels overhead can be too hot overhead. What is the right temperature? Calculate the radiant temperature increase at head level due to the panels and limit this. BS7726 gives a calculation method that can be used in two ways to calculate: 1. either the maximum width of a panel directly overhead in a room with a low ceiling; or 2. the percentage of the room ceiling that can be covered by panels in a room with a high ceiling.

44 Combined Radiant and acoustic panels Where radiant panels are located in classrooms they are provided with a 40mm acoustic insulation layer to limit the need for ceiling mounted acoustic baffles Frequency

45 Radiant panels Can provide acoustic absorption as well as a heating element [Photos: wings.co.uk]

46

47 EFA approach to standards Separate out: 1. Regulations; 2. Minimum performance standards in support of regulations; 3. Non-statutory guidance Where possible use performance in use standards that are measurable rather than use design standards that cannot be measured. Make the performance standards as simple and possible Update the standards as regularly as necessaary, usually every 5 years but 10 years at a maximum.

48 Research cycle 1. Identify and understand problems 2. Explore options to find cost effective solutions 3. Model and pilot solutions 4. Change specifications to improve designs 5. Assess performance in use of resulting buildings through Building Performance Evaluation and user feedback 6. Repeat process if necessary 7. Consider producing new performance standards and guidance that eliminates old design problems

49 The way forward: challenges Design teams, EFA and TAs understand the new environmental standards, eg, Energy in use modelling, Climate based daylight modelling and LENI calculations, adaptive thermal comfort modelling, Thermal models for prediction of cold draughts, prediction of asymmetric radiation from hot surfaces, etc.

50 Performance in Use, Energy Monitoring and Building Performance Evaluation, Soft Landings Emphasis on Building Performance Evaluation (BPE) to optimise the steps towards achieving resource efficient buildings.

51 EFA Guidance, tools and templates Already available on gov.uk, and tested in PSBP: Facilities Output Specification (FOS) Baseline designs Building Bulletin 103 (Area Guidelines for Mainstream Schools) Schedule of Accommodation tool (SoA) for mainstream schools Coming soon, to be tested in PSBP2: Building Bulletin 104 (Area Guidelines for SEN) Area Data Sheets (ADS) Briefing guide (template) Refurbishment guidance 51

52 Environmental Guidance, tools and templates EFA Daylight Design Guide, January 2014 EFA Energy Efficiency guide should inform energy modelling and describes more about energy monitoring and reporting. EFA Draft guide on specification of LED Lighting 2014 BB edition- new Acoustic performance standards Ventilation, thermal comfort and indoor air quality guide to replace BB101 in 2016 some changes from FOS 2014, updates guidance in BB101 Link to acoustics, lighting and ventilation publications

53 Design Project Documentation for PSBP Facilities Output Specification (FOS): Generic brief School-specific brief (template) Schedule of Accommodation tool Area Data Sheets Guidance and context documents to assist: Baseline designs Briefing guide/ refurbishment guide Building Bulletins 103 and 104 Typical FF&E layouts