Building an even better Passivhaus School

Building a Better Passivhaus School19th International Passivhaus Conference Leipzig 2015

Nick GrantAlan ClarkeElemental Solutions

@ecominimalnick@AR_Clarke

Three Schools One TeamOakmeadow Bushbury Hill Wilkinson

© Dennis Gilbert/VIEW

Team:Architype, Thomas Vale, E3, Ion Acoustics, Price and Myers, Elemental Solutions

www.architype.co.uk

2012 RIBA West Midlands Winner2012 UK Passivhaus Trust Awards2012 RIBA Special Award winner

Oakmeadow(no extra budget for Passivhaus)

Image Courtesy Architype

Images Courtesy Architype

Bushbury Hill(no extra budget for Passivhaus)

Image Nick Grant

Image Nick Grant

Image Nick Grant

Pending

Image Courtesy Architype. © Dennis Gilbert/VIEW

Wilkinson(10% less budget than the others)

Structural slab

Air tight layer

Load

Image: Architype

Basic construction the sameTimber frameCellulose insulationOSB air barrierLevel accessFloating slab on 250mm EPS


On site: October 2012, Complete: December 2013


Client: Wolverhampton City CouncilValue: £5,000,000 (€6,800,000)


TFA: 2395m2

Kids: 420

Image Courtesy Architype. © Dennis Gilbert/VIEWImage Courtesy Architype. © Dennis Gilbert/VIEW

Images Courtesy Architype. © Dennis Gilbert/VIEW

Key Lessons• IHGs – higher than in German schools• Fenestration – less is more• Ventilation – proof of original concept plus simplifications• Kitchen – mature solutions refined• Heating – one small boiler and radiators• DHW – losses dominated so electric used• BMS – still not resolved, do we need one?• Occupant feedback crucial for learning

IHG due to KiddyWatts Average for UK examples 5.7 m2/childAverage for German examples 10.5 m2/child

Difference in body heat = +1.32W/m2

+ 5-6 kWh/(m2.a) of useful heating(Against 15kWh/(m2.a) target)

Image; Nick Grant

IHG

Meant Less South Glazing

Image Courtesy Architype. © Dennis Gilbert/VIEWImage Nick Grant

Can Afford More Shading



Minimised Glazing to Ground

Image Architype. Juraj MikucikImage Nick Grant

• Reduced cost• Less winter heat loss and summer gain• More useful space• Better daylight

Higher IHG ‘cheat’;

So how much did heat demand increase with less solar gain?

Wilkinson gas use 1 year

Special needs

school

Pre Passiv

BREEAM Excelle

nt

Oakmeadow

(inc’

DHW)

Bushbury

(inc D

HW)

Wilk

inson

(Electric

DHW)

Imag

e A

rchi

type

Electricity

Image Architype

Wilkinson(inc Electric DHW)

OakmeadowBushbury

Lowest of group but still higher than hoped.

Note St Luke’s has window ventilation

Energy Use First Full YearGas for space heating 9.1 kWh/(m2.a)Gas for kitchen DHW 1.2 kWh/(m2.a)Electricity 51 kWh/(m2.a)

PE 144 kWh/(m2.a)

High electric use not yet diagnosed but prime suspect is accidentally connected heater battery in kitchen vent and BMS control fault of MVHR. Good summer comfort indicates internal gains are as anticipated.

Summer Comfort Greatly Improved

“The questionnaire survey of staff members in 3 passivhaus schools found that Wilkinson classrooms were on average, better rated in terms of thermal comfort and indoor air quality.”Chryssa Thoua, Architype. KEEN Project to be published 2015 with graphs & data.

KEENPost occupancy monitoring as part of Knowledge Exchange and Enterprise Network (KEEN) project between Architype and Coventry University, led by the University of Wolverhampton and funded by European Regional Development Fund (ERDF) and Architype.

Cascade vent used in all 3 schoolsWorks well, simple control, lower cost

MVHR

First floor ventilation schematicImage Architype, Chryssa Thoua

Summer ventLeave MVHR running in summer?•Better air quality•Easy to understand•Simpler WC vent

Graph courtesy Architype, Chryssa Thoua

ppm

CO

2

German Primary School window

Not allowed in UK!Alan Clarke Passivhaus Building Services design & occasional stuntman

Full commercial kitchens

Key points for kitchen vent• All electric – no combustion products• Variable speed air flow – comfort• Robust 50% heat recovery delivers comfort. 12°C fresh

air is fine in kitchen, don’t need 17°C

Wilkinson improvements:• Eliminated heating coil & so frost coils• Electric heater fitted (against our advice) as fall back

measure but was to be isolated

Kitchen Vent

Download the paper and presentation: www.elementalsolutions.co.uk

The Heating System• One boiler for 2,400m2 building (84kW, <25kW demand) • No weather compensation• Radiators and TRVs You sure this is the

right boiler?You sure this is the

right boiler?

Four times the size they needed apparently

Four times the size they needed apparently

Image Nick Grant

Hot Water• With gas, circulation losses dominated, over 60%• Local electric but only 7 units for whole school• 8mm copper pipe for longer pipe runs so less heaters• 2.7kWh/(m2.a) PE standing loss• Instantaneous gas in kitchen (c.a. 1.2kWh/(m2.a)

1.7 litres/minute ‘sprays’Proof of concept test rig

BMS/BEMS“Critics of BMS would do well to remember how building services were controlled in the past. The simple controls that used to be the norm – such as time clocks and thermostats – were often either never adjusted or they were subject to unauthorised tampering, resulting in huge amounts of energy being wasted. What solved the problem was the introduction of building management systems. This is one reason why such systems are now the dominant form of HVAC control in non-domestic buildings.”

Trend website

BEMS• Claimed to save energy.• Say £50k install, £5k/a tech support contract,

sensor & actuator testing etc• Gas bill £1.5k/a so potential ROI=??• See papers by Prof Axel Bretzke Frankfurt

One bit logic problemBMS allows us to do clever thingse.g. WC vent in summer using MVHR

1 & 0 swapped in BMS logic – extract air damper to hub space shut in winter mode.

•Spotted because of cool supply air (due to vent imbalance)•High fan power all winter (and noisy!)

BMS 2020?“Critics of simple controls would do well to remember how building services were controlled in the past. The complex BMS controls that used to be the norm were often either never adjusted or they were subject to unauthorised tampering, resulting in huge amounts of energy being wasted. What solved the problem was the introduction of simple thermostats and timers. This is one reason why such systems are now the dominant form of HVAC control in non-domestic buildings.”

A light switch, KISS(Safety gear optional)

Image Nick Grant

Schools Conclusions

• Higher IHG assumption led to more comfortable building & paradoxically lower heating demand

• Design simplification takes time and courage but can save money and improve performance

• If something can go wrong it will but if it isn’t installed it can’t go wrong.

• Thanks for listening!