@Green July/August 2021 | Page 21

July-August , 2021 | @ green

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Solar facade panels as glass spandrel ( left ), as façade panels ( middle ), as printed artwork ( right ). The technologies are AGC ( left and right ) and Kromatix ( centre ).

and the reasons mentioned above , allowing for some degree of off-site renewables for some building types might be a reasonable solution going forward .

Solar panel window façade ( left ) with the view from inside ( right ). Technology by AGC .

a whopping 93 per cent of the facade .

This would significantly limit the amount of façade glazing for daylight and views out unless , of course , the windows themselves produce electricity . This technology is available but not yet widely used .

Had the office building been designed without energy efficiency , the BEI would be 250 kWh / m2 / year . Covering the entire roof ( 1,200 m2 ) and façade ( 28,125 m2 ) with solar panels would only achieve 13 per cent renewable energy reliance .

In other words , energy efficiency must be pushed really hard for high-rise commercial buildings to have a chance at meeting the 30 per cent renewable energy requirement .

Energy efficiency as key strategies

The above case studies showed that several building types will face difficulty meeting DBKL ’ s new onsite 30 per cent renewable energy requirement unless the buildings are designed to be energy efficient .

High-rise office buildings must be designed to be very energy-efficient with a BEI of 90 kWh / m2 / year or lower , or else the building roof and façade has insufficient space for solar panels to produce the required energy .

Buildings can be thought of as leaking buckets , where energy wastage is symbolised by leaking water ( see cartoon ).

Instead of blindly pouring more and more water into the bucket , the leaks should be plugged in first .

In other words , the buildings should be made energy-efficient before adding solar panels . This combination of energy efficiency and renewable energy is the right and cheapest way forward to reduce energy consumption , energy costs , and carbon emissions .

Our simplified online calculator allows building designers to determine what combination of energy efficiency and renewable energy will meet DBKL ’ s 30 per cent renewable energy requirement : www . ien . com . my / pv-calculator

The emergence of electric vehicles , which often will be charged in the car park at offices and homes , will significantly increase the energy consumption of buildings .

This will make it even more challenging to meet DBKL ’ s 30 per cent renewable energy requirement in the future . For this

CARTOON BY BJORN BULL HANSEN , IEN CONSULTANTS

Energy-producing windows and facade panels

Instead of installing “ ugly ” solar panels on the façade , it is now possible to get beautiful façade integrated solar panels that do not even look like solar panels . In fact , solar panels can be printed in any design and become an aesthetic highlight of the building .

Or , more conservatively , they can look like ordinary façade panels in the colour of your choice , including glass spandrels that match the glazing colour of the rest of the building .

Energy producing windows , which have nearly invisible solar cells embedded in the glazing , are now available on the market . This product makes good sense in the tropics , where windows typically cut away half of the sun ’ s energy anyway .

So , why not do so with embedded solar cells and produce electricity at the same time ? Windows typically make up about 30-60 per cent of the façade area , so for high-rise buildings , the use of energy-producing windows can contribute significantly to achieving DBKL ’ s 30 per cent renewable energy requirement .

Kuala Lumpur has set a target of becoming a carbon-neutral city by 2050 . Currently , 41 per cent of Kuala Lumpur ’ s carbon emissions come from residential ( 10 per cent ), commercial ( 24 per cent ) and industrial ( seven per cent ) buildings .

By imposing the 30 per cent renewable energy requirement , DBKL is killing two birds with one stone by effectively forcing most new buildings to implement both energy efficiency and renewable energy measures . An excellent first step on the critical journey to a fully decarbonised society . — @ green

Austin Lim is from IEN Consultants Sdn Bhd - a pioneering green building consultancy in Malaysia with a specialisation in energy-efficient and healthy buildings .