the importance of daylight 3

DAYLIGHT AND ENERGY EFFICIENCY

ANOTHER ASSET OF DAYLIGHTING IS ITS POTENTIAL FOR MINIMISING THE ENERGY CONSUMPTION OF BUILDINGS. LIGHTING REPRESENTS ROUGHLY ONE QUARTER OF THE ANNUAL ENERGY DEMAND IN A TYPICAL RESIDENTIAL BUILDING AND THREE QUARTERS IN A TYPICAL OFFICE BUILDING (WITH STANDARD INSULATION AND NO ACTIVE COOLING SYSTEM). THE HEAT GENERATED BY LAMPS AND OTHER FIXTURES ALSO RAISES THERMAL LOADS. CONSIDERING THAT BUILDINGS ARE RESPONSIBLE FOR AROUND 47% OF CO₂ EMISSIONS WITHIN THE EUROPEAN UNION, ELECTRICAL LIGHTING HAS A DRASTIC IMPACT ON CLIMATE CHANGE.

THE ADVENT OF ELECTRICAL ENERGY AND THE DEVELOPMENT OF INDUSTRIALIZATION IN THE NINETEENTH AND TWENTIETH CENTURIES, PARTICULARLY THE VAST USE OF FLUORESCENT TUBE LAMPS IN DEEP PLAN OFFICES, BROUGHT ABOUT A TYPE OF BUILDINGS EXTREMELY DEPENDENT ON ARTIFICIAL LIGHT. TODAY, DUE TO THE INCREASING AWARENESS OF THE BENEFITS OF DAYLIGHT, THE TREND OF THE GOOD ARCHITECTURE IS TOWARDS A SYNERGY OF NATURAL AND ARTIFICIAL LIGHTING. THEY SHOULD COMPLEMENT EACH OTHER, AS CALDAS AND ROCHA (2001, P. 256) REMARK: “THE ARTIFICIAL LIGHTING SYSTEM IS SUPPOSED TO BE CONTINUOUSLY DIMMABLE AND TO PROVIDE JUST ENOUGH LIGHT TO MAKE UP FOR THE DIFFERENCE BETWEEN AVAILABLE DAYLIGHT AND DESIRED SET POINTS”.

IMPROVING DAYLIGHT DOES NOT MEAN INCREASING AS MUCH AS POSSIBLE ITS AMOUNT, MAXIMIZING THE SIZE AND PROPORTION OF GLAZING. TOGETHER WITH LIGHT, WINDOWS PROVIDE OTHER DESIRABLE ELEMENTS, LIKE SOLAR RADIATION CONTRIBUTING TO PASSIVE SOLAR DESIGN, VIEWS OUT, VENTILATION AND SOUNDS, BUT ALSO UNDESIRABLE ELEMENTS, LIKE EXCESSIVE HEAT GAINS OR HEAT LOSSES, GLARE, NOISE AND AIR POLLUTION, WHICH MUST BE CONTROLLED.

SUCCESSFUL DAYLIGHTING DESIGN MEANS ACHIEVING A BALANCE POINT BETWEEN SUCH STRENGTHS AND DRAWBACKS, THUS REDUCING THE ENERGY DEMAND OF NOT ONLY ELECTRICAL LIGHTING BUT ALSO MECHANICAL SYSTEMS FOR COOLING AND HEATING, TO PRODUCE A TRULY ENERGY EFFICIENT BUILDING WITH LOW ENVIRONMENTAL IMPACT.

ON THE WHOLE, ONE OF THE DESIGNERS’ CHALLENGES IS TO WORK WITH THE INTERDEPENDENCE OF THE EMOTIONAL, PHYSIOLOGICAL, FUNCTIONAL, AESTHETIC, ECONOMIC AND ENVIRONMENTAL ASPECTS OF DAYLIGHTING.

REFERENCES 

Augustesen, Christina et al., Lighting Design: Principles, Implementation, Case studies, ed. by Nicola Kollmann and Christina Schulz (Basel: Birkhauser, 2006)

Caldas, Luisa and Joao Rocha, 'A Generative Design System Applied to Siza's School of Architecture at Oporto', Caadria, 3 (2001) 253-264 <http://wwwfaculty.arch.usyd.edu.au/ kcdc/journal/vol3/caadria/Caldas.pdf> [acessed 06 Nov 2009]

Smith, Peter F., Architecture in a Climate of Change, 2nd edn (Oxford: Architectural Press, 2001)