Transcript Tubular Daylight Guidance Systems: building codes and the

Tubular Daylight Guidance Systems:
building codes and the environment
Mohammed Al-Marwaee and David Carter
School of Architecture
University of Liverpool
Daylight guidance systems (DGS)
Tubular guidance systems redirect daylight into areas of
buildings that cannot be lit by conventional glazing.
Tubular daylight guidance technology
1. Active collectors
These track the movement of the sun
using mirrors and lenses (heliostats),
but incur a high capital and control cost.
2. Passive collectors
These are essentially vertical tubes
capped by a light collector, and are
commonly used for task and amenity
lighting.
Passive zenithal
Passive zenithal collector
Light guides
Guides made of aluminium
sheet coated with either silver
(95% RF) of multilayer plastic
(99% RF)
Straights and bends available
Passive zenithal emitter
Passive zenithal emitter (2)
Fits 600mm
ceiling module
Building codes regulation
• Structural stability
Stability and integrity under wind & dead loads
• Fire protection
To prevent fire spread over surfaces, fire and smoke spread within and
between buildings, and ensure fire separation within and between adjoining
buildings
• Materials durability and weatherproofing
Ensure durability of materials in long term use. Stability of materials under
prevailing climatic conditions
• Thermal considerations
To conserve energy by minimising heat loss and gain
• Lighting issues
Most regulations refer to electric lighting but most Codes encourage the use of
daylight
Building codes - Structural stability
• Few structural implications for TDGS
• Heliostats require additional structural work to account for wind and
dead loads
• Transport elements have small dead load but must not conflict with
structural beams etc
Building codes - Fire protection
• Regulations for fire protection are based on similar principles
worldwide
• Prevent and fire and smoke spread within buildings using fire
compartments
• Prevent fire spread over surfaces by using non -combustible materials
• Fire separation between adjoining buildings
Fire and smoke within buildings and
TDGS
• Both vertical and horizontal transport components of TDGS may pass
through compartment enclosures
• Fire protected ducts or cladding used for vertical routing through
compartments in multi-storey buildings
• TDGS must be fire-stopped whenever they penetrate fire-resisting
walls, floors and ceilings using fire dampers
Fire and smoke between buildings and
TDGS
• Spread of fire between buildings is controlled by limiting the area of
unprotected building envelope glazing aperture
• The optical efficiency of TDGS compared with conventional roof lights
can have a beneficial effect of limiting unprotected roof aperture
• TDGS present no greater risk of internal surface spread of flame than
electric lighting luminaires being made of similar materials
• Majority of TDGS are in single storey buildings - that is into one
compartment and most codes allow penetration of the building
envelope alone
Lighting and TDGS
• TDGS can be used to provide daylight into areas of buildings far from
the building envelope
• TDGS are capable of delivering useful quantities of daylight dependant
on the configuration of the interior and the lighting system and its
controls – up to 2% Daylight Factor
• There is a need for daylight linked electric lighting to permit
substitution by daylight
The environment and ‘climate change’
• ‘Climate change’ is a major crisis facing mankind
• Attempts to address the problem have concentrated on reduction of
greenhouse gases, notably CO2, by reducing emissions
• The largest consumers of energy in most countries are within the
building stock
• Daylight can reduce the environmental impact of lighting by acting as a
Lighting is a major consumer of energy
• substitute for electric light
• Daylight is more efficient than electric light, its efficacy being of the
order of ten times more than that of an incandescent lamp and
therefore can lower the cooling requirements of a building
Building Codes and CO2
• Energy usage and CO2 emission is the main criteria for
satisfying the energy-related parts of European Building Codes
• Assessment is carried out using software from input of a
description of the building geometry, construction, use and
HVAC and lighting equipment
• The provision or otherwise of daylight within a building is a
major part of the assessment procedure
• Work by the authors suggests that buildings that would not
otherwise gain Building Code approval would do so with the
addition of light guides
Case studies of installations
1- University building
• Top floor of existing three storey building.
• Penetrates roof only
• Small unprotected roof area
• Provides insufficient daylight for tasks
• Electric lighting not daylight linked
• Daylight linked TDGS reduces the annual
CO2 emissions by 20.7 mT. (85 %).
2- Office
• Two storey office
• 12m guides in roof space require support
• Conflict with other services in roof
• Guides not fire protected
• Makes substantial contribution to task illuminance
• TDGS will, assuming daylight linking, reduce annual
CO2 emissions by 1.2 mT. (41 %).
3- School
• Purpose built two storey
• Guides to upper floor penetrate only roof
• Guides to lower floor in brick vertical duct
• Not enough guides to provide sufficient task illuminance
• TDGS will, assuming daylight linking, reduce annual CO2
emissions by 1.1 mT. (61 %).
4 - Villa Fida
• Three-storey villa in Riyadh, Saudi Arabia
• .Most of the guides installed in the basement
• Collectors in garden rather than the roof and integrated into
landscape and at night the guides transport internal lighting to the
garden
• TDGS will, assuming daylight linking, reduce annual CO2
emissions by 1.1 mT. (41 %)
4600sqm warehouse lit using 105No
650mm dia guides
A
daylit
cave!
Conclusions
•
Codes do not specifically refer to TDGS.
•
Codes treat collectors as rooflights, transport
elements as pipes or ducts, and emitters as
luminaires.
•
Still need for new products- eg. Low optical loss for
protection at compartment walls and prefabricated fire
resistant cladding.
•
The technical development of system components has
arguably outstripped consideration of practical issues
of detailing and buildability.