Introduction
A well performing shopping mall should fundamentally have proper Indoor Environment Quality. The importance of a high proper Indoor Environment quality; be it in terms of thermal comfort or air quality cannot be underscored any more. Significant energy goes into creating a high proper Indoor Environment Quality in shopping malls. This energy is used for processes like cooling and ventilation in order to get rid of the high internal gains in heat from electrical appliances, equipment and people. In the recent past, architects have explored the potential for natural ventilation in building spaces (Bauer, MöSle, & Schwarz, 2010, pp.71)
Following up on their advances, architects have applied natural ventilation in non-domestic buildings to positive effect. Buildings such as offices and schools have been planned to allow natural ventilation and the results have been occupant satisfaction and high proper Indoor Environment Quality. The upside of these ventures has been tremendous savings in the costs of running the buildings. More precisely, the energy costs incurred in using mechanically run ventilation mechanisms have been greatly reduced. Owing to the significant benefits that natural ventilation presents, the lingering question is how to achieve increased efficiency.
In prospect, changes in designs of the shopping mall buildings might be the key to achieving increased efficiency. This is because the current designs feature an open space and retail outlets on either side. Whereas the open mall space can be naturally ventilated, the private retail outlets have their own cooling systems that pass cool air from the exterior into the central open space in the mall. In exploring various designs, this paper will highlight the benefits of natural ventilation in shopping malls. In doing so, the paper will delve into reports and a case study offering relevant figures, ratios, diagrams and an analytical view of various approaches into natural ventilation in a shopping mall.
This question is of grave importance to the module and for general knowledge. It offers a glimpse into the amount of energy used to by establishments in order to maintain thermal comfort. For instance, Standring & Buchanan-Smith, (2012, pp. 2) adduce that malls in landlord areas use up to 33 kWh/m2/y and 3 units of gas in naturally ventilated unheated street spanning 111480m2 and 49 kWh/m2/y of electricity and 59 units of gas to maintain thermal comfort in HVAC enclosed shopping mall spanning 60358m2. While the module talks about energy consumption in ventilating establishments, this essay delves into the effects of natural ventilation design in a shopping mall with figures to show how savings on energy can be made.
This study presents the upper floor of a shopping mall in London, United Kingdom designed to have an opening directly in the façade. The design also features access to the aperture in the atrium and lantern. The ventilation principle is illustrated using the diagram below:
Fig 1: The upper floor of a shopping mall designed to have an aperture directly into the façade (Diederichsen, Friis, Brohus &Tranholm, n.d. Pp 2.
The natural ventilation passes via the automatically controlled aperture in the façade. It also passes in the upper aperture of the lantern. The façade is designed slanting towards the direction of the sunrise with the exhibition windows provided with external solar shading. The external solar shadings prevent the entry of heat from the sun thereby heating the shopping mall. Consequently, there was a shading coefficient of 0.35. The windows adjacent to the facades have a g-value of 0.4 corresponding to the total amount of solar energy transmitted to the shopping mall by the windows which amounts to 40%.
The g-value refers to gain in temperature due to transference in solar energy into a space or object. Normally, g-values range from 0-1 with lower values indicting lower gains in temperature via solar energy. Notably, the internal solar shadings have considerably reduced solar gains, hence the solar gain coefficient of 0.4 for the glass. Although the figure is relatively high at 0.4, especially because the exhibition windows have inters solar shadings. These passive energy control techniques go a long way to augment the natural ventilation design in the mall.
In order to assess the achieved Indoor Environment Quality during all seasons, thermal simulations for this case alongside two other were carried out for twelve months. The significant internal heat loads from the electronic appliances, equipment and people in the retail outlets in shopping malls require a high flow rate of air during opening hours. Owing to the fact that the air supply inlet is air from outside the shopping mall where the air is presumably cooler, there exist no issues with the carbon dioxide levels.
This is because there is sufficient circulation and due to the carbon dioxide cycle in the atmosphere, the levels in the air are kept sustainably normal. In an assessment run concurrently with the thermal simulations, the carbon dioxide concentrations in all zones of the shopping mall corresponded with the class II; that is carbon dioxide concentrations of 500 parts per million above outdoor concentrations. Going by the evidence above, one can correctly infer that as far as air circulation goes, natural ventilation in the shopping mall is feasible (Coleman, 2010, pp. 147). This is of course in regards to one of the aspects of Indoor Environment Quality; that is air quality.
Time (% of the year)
Fig2: A line graph showing the air flow rate versus the time (% of the year) Diederichsen, Friis, Brohus &Tranholm, n.d. Pp.5
The figure 2 shows the air flow rates during the twelve months of thermal simulation and illustrates a sum-curve of ventilation rates. The figure shows that the automatically controlled natural ventilation has the ability to remove the whole heat load in several periods of the year. Although the solar gains increase during the summer, the effectiveness of the natural ventilation method relative to the mechanical method is noteworthy. During the summer periods, mechanical mechanisms of ventilation have to supplement natural ventilation in order to acquire the appropriate levels of Indoor Environment Quality.
Benefits of natural ventilation
Natural ventilation presents a wide array of benefits that an architect can exploit in constructing a shopping mall that maintains a high Indoor Environment Quality all year long (Thompson, 2000, pp.2). The following is an analysis of some of the benefits of natural ventilation in a shopping mall:
- Capital cost saving
Compared to the mechanical heating and air conditioning, natural ventilation has tremendous capital savings. More precisely, the Chartered Institution of Building Service Engineers (Standring & Buchanan-Smith, 2012, Pp. 5) outlines a benchmark comparison of the order of 15% in capital cost savings for naturally ventilated buildings compared to air conditioned buildings. In this context, capital cost is the financial input required in constructing a shopping mall, or any other construction for that matter. A saving of 15% on the capital cost during the construction is considerable.
- Reduced energy consumption
Retail schemes in shopping malls dominantly use electricity for associated cooling and lighting. This extensive use of electricity raises the amount of power used throughout a financial year. When this is converted into monetary terms, the cost implications are mind boggling. The increased costs cut in on the profit margins made by the shopping mall. Reports have shown a 50% decrease in annual electricity usage, in shopping malls where natural ventilation was employed over mechanical ventilation. The following is a comparison of energy consumption in two live schemes.
Key
The table above shows a 33% reduction in electricity usage coupled by a significant diminution in the usage of gas due to the verity that there is no heating in the naturally ventilated scheme as evidenced by the data from the common meters to monitor energy usage. This shows evidence that it is beneficial for architects to incorporate natural ventilation in shopping malls.
- Less maintenance required
Reduced maintenance costs are a benefit to the shopping mall because they in turn reduce the running costs. Unlike mechanical ventilation or air conditioning, natural ventilation does not require plant and equipment replacements and energy consumption this further reduces the service charged applied on the shopping mall annually. The following is an illustration of the average service charge including any exceptional expenditure for shopping centers adduces more evidence on the cost effectiveness that natural ventilation has.
The following is a graphical representation of the information tabulated above for more perspective.
Fig3: A bar graph showing the comparison between the cost of air conditioning and natural ventilation.
- Lower plant and equipment space requirement
Unlike other ventilation mechanisms, natural ventilation uses up less plant space. Compared to the HVAC which uses 5-8% of the plant space, natural ventilation uses 2-5% of the plant space. The extra space can be employed to augment net to gross ratios. The following is a graph illustrating the use of space by HVAC systems.
Fig 3: A bar graph showing the use of space by HVAC systems (Standring & Buchanan-Smith, 2012, pp. 3)
- Compliance to building regulations
Natural ventilation helps construction of shopping malls comply with building regulations. Building Emission Rate is a very important aspect to mull over when constructing a shopping mall. The assessment of the Building Emission Rate is dependent on whether the shopping mall is occupied for a significant part of the day (Allard & Ghiaus, 2005, pp.15). In instances where the shopping centre is ventilated naturally and is unheated, the covered street area is removed from the assessment. By naturally ventilating the shopping mall, the construction is able to meet the standards regarding energy efficiency and the U-Values showing thermal transmittance. Natural ventilation also helps reduce the impact of solar gains during hot weather. Assessments are also made to see whether there is extensive glaze.
Conclusion
The study, while alluding to the a case study of a shopping mall in London, showed the effect of natural ventilation on the Indoor Environment Quality; this being the thermal comfort and air quality. The essay showed that the internal solar shadings considerably reduced solar gains, hence the solar gain coefficient of 0.4 for the glass. This in turn reduces the heat load gains in the shopping malls hence enhancing thermal comfort. The essay also shows the effect of natural ventilation on indoor air quality. Through natural ventilation, air from outside flows in and out of the shopping mall thereby creating a circulation that brings in fresh air and rids the building of stale air.
Of great concern are the carbon dioxide levels inside the shopping mall. However, assessments showed that the levels were in the Class II region which is 500 parts per million above the outdoor concentrations. The essay also presented facts to support the benefits of natural ventilation. With the tremendous benefits that natural ventilation presents, existing orthodoxy is expected to change in approach. The case has shown tremendous saves in energy compared to air conditioning and mechanical ventilation methods. Contemporary designers have something to ponder about given the exploits presented by natural ventilation. This notwithstanding, more research is required in order to fine tune the concept of natural ventilation. The findings of the essay are also green fodder for policy makers given the need for conservation of energy. The architectural and the construction industry might be revolutionized through the perfection of natural ventilation through research. However, this essay only considers one case study, and it might not be efficient to form a basis. Nonetheless, the facts from the case study are without doubt mind opening.
References
Allard, F., & Ghiaus, C. 2005. Natural ventilation in the urban environment: assessment and design. Sterling, VA, Earthscan.
Bauer, M., MöSle, P., & Schwarz, M. 2010. Green building: guidebook for sustainable architecture. Heidelberg, Springer.
Coleman, P. 2010. Shopping environments: evolution, planning and design (W druku na żądanie. ed.). New York: Routledge - Taylor & Francis Group.
Diederichsen, Friis, Brohus &Tranholm, n.d Potential of natural ventilation in shopping centers. Available through http://vbn.aau.dk/files/14951894/Potential_of_Natural _Ventilation _in_Shopping_Centres
Standring, I. & Buchanan-Smith, M. 2012. Shopping Center Natural Ventilator Design. London. BCSC
Thompson, M. 2000. Principles of Natural Ventilation. Available through http://www.gse. cat.org.uk/cpd/pluginfile /Airtightness%20and%20ventilation.PDF.[Accessed on] 29 December 2012
