Civil Engineering Materials and Sustainability - Case Study Example

Table of Contents Introduction…………………………………………………….…………………………..3 Clay Bricks………………………......................………………...……………………….3 Light Weight Timber..................................................................................................4 Concrete Slab Floors..........................................................................................…...6 Passive Solar Heating...............................................................................................7 Skylights.....................................................................................................................9 References…..............................................................................................................11 Introduction The essay gives a detailed discussion of some of the materials used in the construction or the art gallery and the environmental aspects of these civil engineering materials. Two sustainable designs are also included which will make the art gallery an environmentally friendly building. Civil Engineering Materials Clay Bricks Clay brickwork is made from selected clays that are moulded or cut into shape and fired in ovens. The clays are thus transformed into building component having excellent weathering qualities as well as high compressive strength. Clay bricks are thus very popular material since ages for use in construction. Clay bricks are readily available because of the mass production and can be thoroughly tested for strength. There relatively high mass is regarded for their desirable acoustic and thermal properties. Affordability is another feature which makes the clay bricks very much desirable as a civil engineering material. Once used in construction, clay bricks do not require maintenance and possess high durability and load bearing capacity as well. The clay bricks are to be used in all the walls of the art gallery i.e. the partition as well as the load bearing walls. The ability of the clay bricks to support suspended floors in addition to the roof and walls in the storey above can be utilized in the walls of the ground floor particularly the walls of the entrance hall and the lobby which are acting as load bearing walls. The windows and doors can easily be incorporated in the clay brick walls. Most commercially available doors and windows are manufactured to be compatible with clay brickwork and same is the case with the proposed design of the windows and doors in the art gallery building that is the cavity construction. The environment friendliness of clay is also justified. Clay brick manufacturer uses source of energy which are non renewable but the investment of embodied energy is repaid by the longevity of the material. The buildings constructed through clay bricks have long lives, low maintenance requirements and thus low maintenance costs. The clay bricks are highly recyclable in nature thus it is a sustainable form of construction. Clay bricks can be reclaimed for re-use when a building is demolished. Brick ballast can also be made from the used bricks which can be used in paths and road surfaces. The use of clay bricks in the walls of the lobby and the entrance hall is very useful as the clay bricks provide excellent sound insulation, particularly for low frequency noises. The specific requirements for sound attenuation can be satisfied by two leaves of 110 mm clay brick masonry with cavity of 50 mm between leaves and 13 mm cement render on each outside surface. Light Weight Timber Wooden structures have been used in all kinds of buildings for many years. Light weight timber construction has a long history in UK construction industry. Timber has the potential to provide a renewable building material when it comes to genuinely sustainable sources. One of the key advantages of timber is that it provides an adaptive material for use in all climatic zones. Light weight timber construction can provide cost effective and flexible design options just as high mass construction materials are most effectively employed when used as part of appropriate design strategies , so there are many situations where lightweight construction may result in a low lifecycle energy use. In the art gallery building the doors will be made from light weight timber as it is the best suited material for that purpose. Also the area in front of the river which will have access from outside will also be made entirely of light weight timber which will provide additional space for displaying wooden art work in a timber constructed environment. Timber frame will support the side walls and two timber columns will face the river side. The claddings and linings of the display galleries and the lobby will be made of timber. Timber is a natural insulator due to air pockets within its cellular structure. Most timbers are extremely low thermal conductors relative to other building materials that is why it is best suited for cladding and lining of the display galleries as the display galleries walls which are directly under the impact of the climate i.e. those are the outer walls of the building so timber will not only serve the purpose of lining and cladding but also will provide thermal insulation. Light weight timber constructions can be designed to incorporate as much or as little insulation as the construction requires and reflective materials can also be easily incorporated. The low thermal conductivity of timber will minimize the occurrence of thermal bridging in the art gallery which will in turn reduce the overall R-value of the structure. Timber is also very good sound insulator and this property will be used in the doors of the art gallery. Also the cladding and the lining of the wall will provide sound insulation in the display galleries. The sound insulation of walls is usually obtained by providing a barrier of sufficient mass to absorb the sound energy, in lightweight timber constructions the wall cavities provide a cushion of air that absorbs sound energy and stops the transmission of sound. Timber is a renewable building resource that absorbs carbon in its production. A lightweight timber construction can be built for deconstruction or easy dismantling, and timbers from the construction re-used or recycled at the end of its use in the building, this makes it a very environment friendly material. Moreover timber is a completely biodegradable material and can be composted if no re-use application is found. So fundamentally timber construction has very low greenhouse gas emissions. Concrete Slab Floors Concrete slab floors are very useful material for construction considering the thermal mass design of sustainable structures. Thermal mass describes the potential of a material to store and re-release thermal energy. Materials with high thermal mass such as concrete slabs or heavy-weight walls can help regulate indoor comfort by radiating of absorbing heat, creating a heating and cooling effect. The floors of the art gallery can be made of concrete slab floors which can be designed to absorb heat form the sun or other sources during winter. Heat can be stored in the slab and re-radiated for many hours afterwards. These floors can also be very useful in summer if the slabs are exposed to cooling night breezes so that heat collected during the day can dissipate. The concrete slab floors can also help in achieving earth coupling as the slab is in direct contact with the additional thermal mass of the earth below which will enhance the performance of the art gallery. Earth coupling can be achieved in the art gallery very easily as the construction is slab-on-ground. Earth coupling will allow the art gallery to achieve the same temperature as of the earth a few meters below the ground surface. This will make the temperature more stable as the temperature of the earth a few meters below the ground surface is more stable (cooler in summer, warmer in winter) Particularly in winter added solar gain boosts the surface temperature of the slab to a very comfortable level. Durability is also a major advantage of concrete slab floor. Concrete’s high embodied energy can be offset by its permanence. This will make the life span of the floors of the art gallery longer than usual. The concrete slabs are also very useful in termite resistance because the shrinkage and cracking is minimized and edges and joints are treated to stop any penetration. The physical barriers are to be employed for the holes of piping in the slabs. This is done by using stainless steel mesh or graded stone. Chemical deterrents can also be used for this purpose but these have to be re-applied at regular intervals to maintain efficacy. The concrete floor slabs are best suited for use in the art gallery because the site is level and thus it will facilitate free flow from of heat from interior to exterior spaces. Suspended slabs will be used in the display galleries which are more desirable aesthetically. The slabs will be suspended on original sub floor walls and footings in the display galleries and the lobby. The concrete slab floor of the entrance hall will be tile fixed by cement based adhesives with different colors and patterns. The finishing of the floor of the lobby will be done by polishing the concrete by trowel finishing through steel trowel finish. The finishing of the display galleries will be done by colored concrete using burnished finishes of dry shake pigments which will be applied to freshly screeded concrete and then the trowelling will be completed. Sustainable Designs: Passive Solar Heating Passive solar heating is a technique which is being used these days in buildings to maintain the temperature of the building utilizing the heat from the solar radiation. Solar radiation is trapped by the greenhouse action of correctly oriented (north facing) windows exposed to full sun. Specific types of window frames and glazing are also used which can easily regulate the in and outflow of heat energy through them as per required. Glazing is very important element of the building envelope. Most of the heat lost and gained is through the glazing in any insulated building. Glazing can transfer both radiant and conducted heat. The glazing areas should be selected properly to maintain a balance between daytime heat gain and night time heat lose and the glazing should not be very excessive because it can be an energy liability then. The windows used in the art gallery are therefore very properly glazed by glass so as to completely follow the principle of passive solar heating. The window frames are of timber which is not a conductor. The trapped heat is absorbed and stored by materials with high thermal mass in the building and this heat energy is re-released at night when it is needed to offset hat losses to lower outdoor temperatures. Another aspect of the passive solar heating is the passive shading which allows maximum winter solar gain and prevents summer overheating. This is done by properly designing the overhangs and deciding the location of the windows. Heat is re-radiated and distributed to where it is needed. Direct re-radiation is the most effective means. The north oriented portion of the art gallery will take the maximum heat of the building and this heat is conducted through the materials and distributed by air movement. The passive solar heating first accumulates the heat energy from the sun in the building and the next step is to retain this heat in the building i.e. to avoid the heat loss. Heat loss is minimized with appropriate window treatments and well insulated walls, ceilings and exposed floors. The floors slabs should not be insulated because the floor slabs are meant to exchange heat from the earth underneath in order to maintain the temperature of the building. The air infiltration also needs to be minimized and this can be done with the help of airlocks, draught sealing, airtight construction detailing and quality windows and doors. In case of art gallery the building is sufficiently air tight and insulated by using wooden frames of buildings, wooden doors and wooden cladding and linings. Skylights Skylights can make major contribution to energy efficiency and comfort in new and retrofit low-rise buildings, which is the case with the art gallery. Daylight is an excellent source of cool light and the right size of skylight admits just the required amount of light. The advantage of cool light is that a given amount of light is accompanied by less heat gain than most types of artificial light. Skylights provide some of the best ways to admit daylight and distribute it evenly, saving energy and improving visual comfort levels. Skylights are very much useful in single storey building or a 2-storey building with open to sky spaces on the first floor which allows skylights for ground floor as well as in the art gallery the open to sky space of the first floor will allow skylights in the display gallery 1 and entrance hall. A skylight can admit more light than windows and thus are very useful and can replace the other sources of light which consume electricity generate excessive heat as well which makes them environmentally very unfriendly increasing the carbon footprint while skylights are sources of cool light. A wide range of skylight shapes are available for sloping roofs and flat roofs as well. Skylights can be of the form of general glazed areas like the atria or sunspaces. The skylights to be used in the art gallery are to be constructed type and only the glazing will be factory manufactured. Skylights will not only save and reduce the energy costs but also improve the lighting quality of the art gallery which is important because certain works are to be displayed under certain lighting conditions. Both of the display galleries will not employ skylights because displaying some artworks will require special lighting effects which can only be provided using the artificial lights which use electrical sources of energy. The display gallery 1 will totally rely on the skylights. Mirrors will also be used to reflect light in the display gallery to make light reach where it is required and to control its intensity. The glazing of the skylight will also contain different colored sheets with the option to incorporate the colored sheet as per the requirement. The entrance hall of the ground floor and the first floor as well will employ skylights. All these rooms which will use skylights will also contain artificial lights which could be used in overcast conditions. The skylights admits more light than windows of the same sizes, but the amount of light entering the building through the skylights can very easily be controlled using long shafts. Even on cloudy days skylights are very much useful because skylights will add some day lit effect to partially artificial lit areas. References: Errol Van Amsterdam (2000) Construction Materials for Civil Engineering, Juta and Company Ltd. Francis J. Young (1998) The Science and Technology of Civil Engineering Materials, Prentice Hall Daniel A. Vallero, Chris Brasier (2008) Sustainable Design: The Science of Sustainability and Green Engineering, John Wiley and Sons Daniel Edward Williams (2007), Sustainable Design: Ecology, Architecture and Planning, John Wiley and Sons J. A. Charles, F. A. A. Crane, J. A. G. Furness (1997), Selection and Use of Engineering Materials, Butterworth-Heinemann Read More