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A change for the better

Existent buildings can be retrofitted to make them greener, says Ivan F. Bartolo.

The LifeMedGreenRoof project at the University of Malta. Photo: Antoine Gatt and Vince Morris.

The LifeMedGreenRoof project at the University of Malta. Photo: Antoine Gatt and Vince Morris.

Today, the word ‘green’ has taken on different connotations. Many technologies and products are being given a shade of green to make them appear environmentally friendly and more acceptable to the consumer. There is also greater awareness of the monetary and environmental costs of energy demand and international legislation is moving towards the concept of carbon neutrality, or of having a net zero carbon footprint.

These influences have pushed new developments to embrace energy efficient design principles by integrating passive solar building design features with the functionality of the building while making use of the latest energy-efficient environmental control systems.

But what about the existing building stock? Many of our buildings would fail miserably not only in an energy audit but also to simply give us the basic material comforts expected by today’s standard of living. We have come to rely too much on technology to remedy design deficiencies leading to overly hot dwellings in summer and conversely buildings that feel colder inside than the weather outside in winter. These inefficiencies come at a cost and depending on systems such as air-conditioning, even with high coefficients of performance, result in high recurrent energy bills.

Malta is blessed with a surplus of daylight especially during normal office working hours

There are ways that we can make our existing homes and offices more energy efficient. Thankfully retrofit solutions within a wide range of prices abound. The difficulty is more often in not knowing what is available, how it works best and where to find it.

Within the next few months, a government initiative funded through the European Regional Development Fund and administered by the Building Industry Consultative Council will be addressing this problem with the launch of a website dedicated to green building technology. The website, www.ecobuild.gov.mt, will be a portal for locally available green building products, suppliers and manufacturers backed by comprehensive educational literature aimed at all levels of the market, from homeowners through to developers and contractors and also technical information aimed at professionals in this sector.

Relatively low-cost improvements that do not usually require drastic changes to the existing building fabric can focus on the main causes of discomfort indoors. These centre on the conditioning of temperature, lighting levels, noise and levels of relative humidity.

One of the top selling features of any property is the amount and quality of sunlight that fills the building. Sunlight helps us understand the sense of space both inside and outside, defining and enhancing the architectural space. Using large glazed areas both as windows and doors as part of modern building design pose a challenge when working out how the rooms within are to perform at their best. Excessive glare creates distraction while the sun’s heat gives rise to hot spots and severe fading of furnishings. The direct sun on the outer fabric of buildings also has a bearing on the solar gain and thermal characteristics within the same buildings. A number of green passive technologies are today available that allow us to manipulate the sunlight available, extending its effectiveness as well as moderating any possible negative issues.

One of the oldest yet most successful means of control is through external shading devices. The variety of shades includes fixed and retractable awnings and pergolas with neutral or coloured fabric, depending on the styling of the building. Open-slatted horizontal timber or aluminium screens installed above apertures also provide shade while letting through sufficient sunlight. These products are available for both the domestic and commercial markets. Traditional fixed and adjustable louvre shutters may no longer be as commonly used as primary design elements but they are still effective in allowing the passage of light and air while keeping out direct sunshine and rain. They also deflect noise while providing a degree of security and visual privacy.

Solar films are designed to be attached on the outside glass surface of windows and doors, even as a retrofit solution. The film helps reflect back solar heat and ultraviolet radiation while allowing most of the visible part of the light spectrum to pass through. The films can be clear or tinted so as not affect the aesthetic appearance of the glazed units.

Depending on the solar film used, it is possible to reduce up to 99 per cent of harmful UV rays which cause our furniture and carpets to fade and discolour. The reduction in solar glare also improves television and computer screen viewing while the reflectance of solar heat contributes to a significant reduction in internal heat gain and subsequently lowering energy cooling costs.

Many of our homes and offices suffer from deep plans with cores which are inadequately lit resulting in an over-reliance on artificial lighting. Although the sick building syndrome is normally linked more to artificially air-conditioned spaces, poor lighting with an absence of sunlight may also contribute to this syndrome.

Great strides have been made in energy efficient lighting systems yet the benefits derived from natural daylight are hard to overlook. With five to six hours of sunshine a day in mid-winter and over 12 hours a day in mid-summer, Malta is blessed with a surplus of daylight especially during normal office working hours. In most situations, it is today possible to introduce natural passive lighting well within buildings by use of light tubes that have highly reflective mirror finish internal surfaces, permitting the light to move through the tube without any loss. These tubes allow light to be bent even at right angles.

An advantage of these light tubes is that this daylight does not introduce an additional heat load since the solar heat fraction of solar light is not transmitted. Such light tubes can easily be accommodated in the depth of modular and gypsum suspended ceilings that are typically used today in both homes and offices.

Other ways to minimise solar gain are by increasing the resistance of the building fabric to the passage of heat. Our roofs are one of the major areas of heat gain in any building. By installing appropriate insulation, especially on the outside of the building, the amount of heat that gets into the building can be significantly reduced. An innovative solution especially suited to our flat roof typology is the installation of green roofs. These are raised plant beds using appropriate growing medium and plants. An example of this technology is the LifeMedGreenRoof project, an EU funded project involving 750m2 of green roof installed over the Faculty of the Built Environment at the University of Malta. The benefits of green roofs include thermal and noise insulation of the underlying roof structure, a reduction in water runoff as well as enhancing the aesthetic value of our rooftops.

If we had to look back at how our ancestors tackled internal climate control given the limitations in the technology options available to them, we would realise the possibilities we have before pressing the button on our air-conditioning remote. Passive ventilation allows natural air to permeate within a building. If harnessed correctly, it would allow the harvesting of cool air currents formed outside under overhangs and other shaded areas to be pulled into our internal spaces through vents and windows that are opened and closed in such a way as to allow exhaust air collecting inside the building envelope to exit and be replaced by clean natural air.

Architect Ivan F. Bartolo is green building technologies project officer at the Building Industry Consultative Council.

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