natural ventilation

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Energy efficient ventilation solutions
Paul Compton
A brief history of Colt

A private company founded in 1931

I J O’Hea OBE (1897 - 1984)

2013 Group turnover £152 million

Manufactures in the Brazil, China, the Netherlands, Saudi Arabia, the
UK and the USA
I J O’Hea,
Colt Founder
Current UK Business markets

Smoke Control

Solar Shading

Natural Ventilation

Louvre

Environmental Comfort Control
Programme

Introduction

Natural ventilation

Mechanical ventilation

Cooling

PIATRA
INTRODUCTION
Environmental
Control Requirements
What’s
important
to you? – Natural AOV
•First cost
•Running cost
•Total cost of ownership / life cycle costing
•Carbon (total or embodied)
•Energy (total or embodied)
INTRODUCTION
Environmental Control
Requirements
– Natural Shafts
Embodied
energy
and carbon
•Accurate information is very difficult to get
•Manufacturers haven’t grasped the nettle
•For most systems it’s outweighed by energy in use
•Aluminium 1tCO2/t recycled, 3-20tCO2/t raw
INTRODUCTION
Environmental
First
cost Control Requirements – Natural Shafts
•Mechanical ventilation – low cost = high energy and carbon in use?
•Natural ventilation – low cost = low energy and carbon?
•Our industry makes first cost so important - specifications are critical
•Approved document L and the associated building services guides?
INTRODUCTION
Environmental
Control
Requirements
– Natural
Shafts
Running
cost
and
total cost
of ownership
•Important to the occupier but not necessarily to the builder
•Soft Landings can help by at least getting the systems set up properly, but if the
design is inherently inefficient ……...
•Reduce loads by solar control, tight building, low energy lighting, limiting plug
loads, etc
NATURAL VENTILATION
Control
Requirements
– Natural
Shafts
-Environmental
If you really
want
low energy
and
carbon
•Generally simple, lightweight systems, therefore with low embodied energy and
carbon
•Virtually no energy use in operation
•But in heated buildings there will be extra winter energy use to counteract the
extra fabric and ventilation heat losses – these can be significant
NATURAL VENTILATION
Environmental
Requirements
– Natural
Shafts ventilated?
So
why areControl
all buildings
not
naturally
•Conditioning of the incoming air is generally not possible
•Close control of internal conditions is generally not possible
•Noise control can be difficult
•Building form may not suit natural ventilation
•Controls need to be well thought through and designed
•Lack of experience/confidence
NATURAL VENTILATION
Environmental
Requirements – Natural Shafts
Energy
andControl
carbon
•Take a simple example of a heated and naturally ventilated
DIY store requiring roof ventilators with 40m2 aerodynamic
area
•Consider 2 options: Colt Seefire or Colt Firelight
Seefire
Firelight
U value
3.5
1.2
Leakage (m3/h/m2
at 50Pa
170
7
£19 000
£30 500
Installed cost
NATURAL VENTILATION
MECHANICAL VENTILATION
Environmental Control Requirements – Natural Shafts
•The embodied energy and carbon of a fan are probably similar to those of an
equivalent natural ventilator but we also have:
ducting, controls, wiring, etc
•Running costs: every kWh typically costs 10p. At an SFP of 1.5 that’s 15p per
hour per m3/s air flow – and there are 8760 hours per year
•With a typical UK power generation mix that equates to 670 kgCO2 and £150
per m3/s per 1000 hours running time.
MECHANICAL VENTILATION
Environmental
Control
Requirements
– Natural
Shafts
How
can we
minimise
energy
use?
•Don’t over estimate the required flow rate
•Limit usage by mixed mode ventilation
•Reconsider duct sizing
•Make ducts as low resistance as possible – simple layouts, minimum bends,
tuning vanes or radiused bends, etc and minimise duct leakage
•Choose efficient fans
•Use VSD control if practical
•Consider EC motors for smaller fans
MECHANICAL VENTILATION
Environmental
Requirements – Natural Shafts
Energy
andControl
carbon
Take the previous example
•Consider the option of using mechanical extract instead
•55 m3/s extract at 0.5 SFP (roof units)
•Initial cost £24000 Running 1000 hours p.a. (summer daytime)
•£2750 p.a. electrical cost, 4500 kgCO2
•Winter heat losses £1300 p.a., 12000 kgCO2
•Overall
•“good” natural ventilation system gives 2 year payback
•“good” natural ventilation system reduces CO2 emissions by 9500 kg p.a.
COOLING
Environmental
Requirements – Natural Shafts
Energy
andControl
carbon
•Three options: refrigerant, adsorptive, adiabatic
•Very different performance and total cost of ownership
•Refrigerant cooling has a high cost but is well established and provides
excellent control of conditions
•Adiabatic provides virtually free cooling, but has limitations
COOLING
Environmental
Control Requirements – Natural Shafts
Adiabatic cooling
•Operates by evaporation of water, converting sensible heat to
latent heat and thus reducing the dry bulb air temperature
•Only operating cost/energy is fan and water pump power. No
refrigerants.
•Ideal for providing cooling under peak conditions when simple
mechanical ventilation is insufficient
•Limitations:
•System LAT floats with incoming air temperature and
humidity
•Cannot dehumidify
•Increases humidity, needs a high percentage FAI
COOLING
COOLING
PIATRA
Environmental Control
Requirements
– Natural
Shafts costs
Comparison
of carbon
and
ownership
•A proprietary Colt program (not available for external use)
•Uses Meteonorm local hourly weather data
•Designed to compare systems, not to give accurate running cost forecasts
•Allows comparison of more than just first cost for Colt systems
•Used to provide the comparisons in this presentation
PIATRA
PIATRA
PIATRA
Design
Installation
Equipment/Controls
Commissioning
Maintenance
The End
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