Building Engineering Services - Research Paper Example

Building Engineering Services Renewable Energy in Buildings Introduction US buildings consume about 36% of the country's energy bill amounting to nearly USD 200 billion. There are two ways of reducing the cost of the energy spent on the buildings; one, by ensuring that the energy is reasonably and optimally used; two, by using renewable energy sources, the total cost on the energy bill could be brought down. Efficiency in employing energy usage in the buildings would reduce the consumption of energy. The other method is to augment energy from alternate sources that are renewable and come in almost free but for the initial investment and maintenance. These are typically, the solar power based energy sources, ground source heat pumps, small-scale hydro, biomass and wind power energy sources (DOE, 1994). Depending upon the location, the nature of the building, residential or commercial, renewable energy sources of appropriate origin can be employed (EERE, 2005). Solar Powered Buildings One of the major reasons for power consumption in buildings is for heating and cooling the buildings (EST, 2006). This consumes almost 42% of the energy consumed by the entire building. If this could be brought under the energy optimisation and under renewable energy portfolio, it could result in immense savings for the buildings. A solar powered energy source is one of the renewable sources that are adopted. Solar energy is a constant and free for use source that is available during the day time and has to be stored to make use of during the night. This is accomplished using two methods of solar energy tapping. One, solar energy is trapped as heat and is used to heat the house or building and it is insulated in such a way that it continues to maintain the warmth in the house through out the day and the night. Secondly, solar energy is also converted into electric energy using the solar photo voltaic cells. This gets saved in the batteries are is directly employed to run the equipments for heating and cooling like the HVAC systems in association with the regular power supply. Solar collectors Transpired solar collectors are used to collect solar heat. These are normally dark, perforated metal wall that would collect almost 80% of the solar heat that falls over it. This is then used to heat the air draught that would provide needed heat for ventilation of the building. Two methodologies are adopted in using the heat collected in the solar collectors. The draught of air gets heated up during the course of the day and continues to heat the entire building as it continues through the night. The other method, heats the water to a high degree from which the heat is distributed through the regular heating lines in the building. Both the methods are used at different locations depending on the convenience. Solar Photo Voltaic Cells Solar panels are extensively used in environmentally friendly buildings to collect the heat of the sun and convert it directly into electricity to enable employing it effectively in all the spheres of work. This has been done extensively in many locations, as roof fitted photo panel; also as separate panels that would help in augmenting the electricity consumption exercises. Ground Source heat pumps These are normally pipes or bores dug into the ground to depths of about 200 to 300 feet is sunk and the additional heat is pumped into the ground during summer and taken off later during the winter when heating is needed. These ground source heat pumps are effectively employed in some of the locations in US and in the rest of the world. It has been repeatedly found that the ground source heat pumps are efficient in pumping in and out the energy, contain it for a period of time and can be used as a large storage space for energy (EST, 2006). These are specifically suited in locations where there is a cooling requirement in the summer and a heating requirement in the winter. Small Scale hydro These are made to use the potential energy of stored water. Water that has accumulated certain potential energy could be used to generate electrical energy when it gets converted into kinetic energy (EST, 2006). Small and micro turbines placed in the piping systems could generate electricity for the purpose of internal consumption. This would be low but still would contribute towards bettering the energy consumption in the building. Though not very much employed, this is one of the areas were research is consistently on and should be developing in the future. Wind Power Energy Systems A tunnel of wind to create the needed draught of wind is created and a turbine is placed inside this to generate the needed wind based energy. Appropriate wind generation technologies are employed to ensure steady and on going generation of electricity since wind provides electricity in thrusts. This is normally placed at the top of the building or at a place which is exposed to least amount of interruption in the flow of wind. This would also result in generation of electric power which could be employed in the manner needed. Effects and uses The renewable energy sources have been employed in a number of locations across the United States and the world. At Adam Joseph Lewis Centre for Environmental Studies at Oberlin College in Ohio, the photovoltaic cells have been used and embedded along with the roof. This building was expected to be 100% energy independent. The roof of the building is laid up with grid-tied 60kW photo Voltaic cells. This was expected to produce an ongoing and continuous source of energy for the building that would make it energy self-reliant and totally dependent on the renewable energy sources. During operation it was identified that PV panels could provide 45% of the energy needs of the building. The building itself was made to energy efficient resulting in an overall energy requirement that was 47% less than the energy needed by an equivalent building under similar environmental conditions elsewhere. Out of this 53%, nearly half of the energy requirement was provided by the solar cells (Torcellini, et al., June 2006). In another location of interest is the Chesapeake Bay Foundation, Annapolis, Maryland. Philip Merrill Environmental Centre is part of the CBF. The building used glazed wall of windows that acted as a heat source during the daytime by providing passive heating for the building and also ensured that there was daylight all over. Excess heating was sent through a heat-pump to the earth as a heat sink. Forty-eight wells each 300ft deep were used to store the heat during the summer months. This also contributed as a heat source during the winter. In order to provide natural draft, the windows were made operable and fans were used to augment air flow. Water conservation was done using the rain water harvesting mechanisms which collected water from the roof and made use of this for garden watering, fire protection systems, clothes and hand washing. As could be seen from the above discussions and case studies, Photo voltaic cells are one of the most common usages of non conventional energy sources that are employed in the buildings. Solar energy is further harnessed using the solar collectors that directly picks up heat from the sun and directly uses it as heat. Where as in the case of Solar panels, it gets converted into electricity and then is employed. The efficiency of such conversions normally work out to be around 40% or lesser. Whereas in the case of direct heat usage, the energy efficiency normally goes well beyond 45% and if only efficient storage of heat or electricity can be done during the peak hour's further usage of the energy during lean periods of generation could be carried out. Of the other forms of renewable energy sources employed, the most common and efficient one is the wind power. It is common to find farms and industries employing wind turbines that would help in generating electricity for internal usage. Though this may not satisfy all the requirements of the company or the industry, it would be in a position to augment the need. The target of some of the experiments today is to find out ways and means by which a combination of such renewable energy sources is made use of to meet the complete needs of the building. Conclusion: While increasing the additional sources of energy is one of the methods to augment energy sources and to reduce dependency on fossil fuels for energy. Energy optimisation and energy efficiencies contribute to the energy usage in the buildings. This would reduce use of energy for lighting purposes, heating purpose and other such naturally available purposes. In addition to this, the energy is also made use of to store and retrieve when needed. Every Watt of power saved is equivalent to generating two watts of power since on one side one unit of power is saved and is spent on the work being executed some where else. References 1. DOE, June 1994, Energized: Building America. 2. EERE, 2005, Use the whole building Design Approach, Building Technologies Program, available at: http://www.eere.energy.gov/buildings/info/plan/whole-building.html 3. EST, 2006, Housing & Buildings: Renewable energy, Energy Saving Trust, available at: http://www.est.org.uk/housingbuildings/renewables/ 4. Torcellini P, et al., June 2006, Lessons Learned from Case Studies of Six High-Performance Buildings - Technical Report, National Renewable Energy Laboratory, available online at: http://www.nrel.gov/docs/fy06osti/37542.pdf Risk Assessment and its implication for Building Design Introduction The nature of risks that the buildings need to undergo can be classified as listed below: 1. Earthquake, flood and natural disasters 2. Fire 3. Terrorist and other intentional damages 4. Other man made risks While the first three are relatively more widely known, the last one stems from happening such as mass exit at the same time which has caused death and destruction due to trampling by fellow human beings, risk due to human mistakes such as a laboratory or an incidental that cause disaster to a large population of the building or the neighbourhood. This could arise out of materials stored in the building or due to the activities that was being carried out in the building and not following due safety precautions. This can also happen in cases where workers in the building employ unsafe practices such as painting without using proper safety belts. All this would result in risks out of other man made activities. Risk Assessment Risk management is done using standard methods. It is important that Assessment of the risk goes through specific methods (Fischert et al, 2002). Risk management is done using a risk management cycle. The list management cycle consist of the following steps: 1. Identify threats to the building 2. Establish what you want to protect 3. Identify vulnerabilities 4. Establish methods to reduce the vulnerabilities and ensure better protection 5. Review your security settings frequently to ensure that there is adequate protection from every envisaged danger. Figure 1: MI5 Security Advice for the buildings (MI5 Security Advice, 2006). These steps are explained in more detail below. 1. Step 1: Identify the Threat The threats to a building come from all these possible sources. It could be close to any of the possible natural disaster areas. Every location is graded depending upon its proximity to earth faults and the earthquake possibility is judged and rated. Similarly, there are possibilities that the place is closer to shore of seas or rivers and might have a higher possibility of flooding. The building may be close to forest zones where it might be prone to forest fires or could be in a volcano zone where the chances of getting hit by a volcano boulder could be higher. Similarly, other possible options like tornado, storms and flooding due to rains could all happen as a natural source of disaster. All these need to be evaluated and a possible threat due to this is to be identified. (Boughton et al, 2006). Similarly threats also happen depending upon the nature of work that is being done in the building. If the building is used to store chemicals somewhere in its basement, it runs into a higher risk of fire or chemical hazard compared to the ones that are not in the nearby zone. If the building is a common meeting place and there is a large number of people who come in and go out, then appropriate exits and entries need to be provided to take care of the large number of people who will be handling it. Failing this could lead to unwanted incidents and mishaps. Emergency fire exits should be capable of taking the complete load in the building. All these possibilities need to be identified to take care of the situations in the building. It is also possible that the building might house some speciality gadgets or might house a bank, then appropriate safety measures need to be taken. The content of the building need to be considered while evaluating the security of the building and its risk factor. There is also a number of intentional threats that could arise from competitors, terrorists and from any other source that only the people operating in the building will be in a position to say. All these possible sources need to be identified and worked upon in order to ensure that the risk is assessed properly. The first step is an essential and important process. If there is a lacuna in this process, then the rest of the processes might be suffering and might not produce the desired results. 2. Step 2: Establish what needs to be protected Once the possible threats are identified it is essential that the object of interest in every possible threat is identified. Unless, we are clear as to what has to be protected, it is not possible to protect the same. From the possible threats, the target for every threat is to be identified. In some cases, this is not a definite object but could be the entire building and the activities that is going on in the building. In order to save the building, the targets for the threats need to be established. In every one of the case, the threat is clearly defined and laid out. It is essential to know what is to be protected from whom in order to clearly safeguard the object of interest from the relevant threats. 3. Step 3: Identify Measures to reduce risk and improve security Now that the threats are known and the objects under threat are also known, the measures that would ensure protection to these objects are known and identified if unknown. These measures are fully analysed and checked for their validity. There cannot be a complete solution for the possible risks in the security of a building. It is not possible to stop the earthquakes from happening or to protect the building one hundred percent from the earthquakes that might occur. However, the damages due to an earthquake can be reduced by suitably designing the building so that it does not get destroyed when the earthquake occurs. Nor does it get disturbed due to a flood. Consciously, buildings built below the basements are hardly affected by a storm or a tornado. This is done as a tornedo shelter. The same way to take care of the risk due to a war or a war like area, where there is a possibility of a bomb getting dropped in the vicinity, it is always felt that a bunker is the safest bet to escape. Such steps in the design of the building will make it all the more safer to live in it either for residential or for commercial purposes. 4. Step 4: Review the security measures and revise plans Based on the security decisions made, they are implemented to ensure that the risk factors in the building are mitigated. The extent to which the risk has been mitigated is to be well understood so that any improvement in it could be done if needed. This review of security and safety has to be carried out on regular intervals. It is important that the safety aspects involved are regularly reviewed and the status is measured where relevant (Home office, 2005). Implications of risks on Building Design Most of the changes in the building due to the risk factors identified is done in the design of the building. Typical examples would be: If the building is expected to be in an earthquake prone zone, then accordingly, changes in the building structure is done to take care of both moderate lateral and vertical movements by inserting appropriate shock absorbers and also by building the entire structure in pieces so that the structure will be able to vibrate with the earth allowing every layer of it to move and dissipate energy. Much the same way, for buildings that are probably prone to fire, then the structure needs to be built using fire resistant and retardant material that would not only stop burning but also retard it. The design of the building would have to be altered to take care of the requirements and appropriate changes need to be made in the design. Conclusion The risk assessment is an essential step in the design process itself. Since every one of the needs to combat risk has to be taken care of by the design and eliminate the hazard meted out by the risk identified. In addition to the risk identified, the identified objects of the risk also need to be clearly identified so that only the specific area that has to take care of the risk could be addressed. In the case of storage of chemicals, only those areas that make up the silos or chemical stores need to be protected. Such steps concentrating on specific areas in the building would help in reducing the cost of the building and in providing appropriate risk mitigation rather than providing an overall cover that could dilute the entire process rather than provide the needed security at the needed place. Computer controlled risk mitigation plans for terrorist strikes are quite common. It is therfore, essential to understand the nature of risks, the object of the risks and then work out a suitable mitigation plan. It is also important that the risks are constantly reviewed and the plans are modified suitably to ensure maximum protection using the state of the art technologies. References 1. Boughton, G. et al (2006), Effects of Cyclone Larry on buildings, James Cook University Cyclone Testing Station, Technical Report No. 51. 2. Fischert, Alvarez M, De La Liera J C, Ridell R, 2002, An integrated model for risk assessment of buildings, SEMC 2001 International Conference on Structural Engineering, Mechanics and Computation, Cape Town, S Africa, Elsevier, Oxford, 2002, Vol.24, pp 841-907 (33 ref). 3. Home office, 2005, Fire Safety - An employer's guide, Crown Press. 4. MI5, 2006, Security Advice - Managing the Risks, Crowns press available at: http://www.mi5.gov.uk/output/Page261.html Read More