Heating and Cooling loads - Assignment Example

Reducing Internal Temperature www.academia-research.com Sumanta Sanyal d: 3/03/2006 Reducing Internal Environmental : Analysing Three Methods Abstract The essay examines ways and means by which the peak internal environmental temperature of a particular building situated in Plymouth, Southeast England, can be reduced to optimum levels to promote comfort and thus productivity among occupants. First the essay posits the physical characteristics of the building and calculations find that the peak internal temperature at above C is much higher than the prescribed comfort level. Next the essay commences with the characteristics of thermal comfort as it is interpreted for the purpose of occupants of an office building. It is found that thermal comfort may be interpreted at levels that fall within the range 24-C for maximum capacity for productivity. The essay next posits three methods to be applied to reduce the peak internal temperature to optimum levels and also puts forward the methodology to be applied. It is also to be noted that te peak temperature is found after computing the mean temperature from records available and calculating the swing in temperature. The maximum swing is computed and added to the mean temperature to arrive at the peak temperature. The three methods actually applied are all hybrid ones in which both passive and mechanised cooling methods are applied. All three methods are found successful in reducing the temperature to optimum levels. This is also done with the application of technology that uses the least possible energy to achieve the maximum results. One of the objectives of the study is to apply cooling techniques that need the least possible energy and this also is found successful with the three methods. Reducing energy usage saves both costs and environmental degradation, as the essay notes. In the end the essay concludes on a successful note having achieved what it has set out to do. Introduction The main purpose of the essay is to analyse three methods by which the internal temperature can be reduced to optimum levels in a particular building with particular occupancy at set times of the 24 hr period day. The specifications of the building are now being taken into consideration together with the existing heat transfer data and the calculated peak environmental temperature that is based on the existing heat transfer data. Building Specifications It is an office in a building in Plymouth facing west. The office is 15m * 5m * 3m with window area totalling 25. The other rooms around this office all have similar specifications. The office is utilised for 8 hrs each 24 hr day. There are 6 occupants emitting 90 W each and 5 electrical items each of 150 W. The doors and windows are closed beyond office time and the ventilation rate is 1.5 air changes per hour. It is also given that the peak solar irradiance on a west-facing window is 625 W/at 1600 hrs on 21st June in Southeast England and the daily mean is 185 W/. The mean solar gain coefficient for the glazing without blinds is 0.25 and the alternating factor is 0.2. The existing thermal data is tabulated below. Table 1.: Heat Transfer Data Surface A(m) U(W/m)K AU Y(W/mK) AY Lag(h) Glass 25 3.3 82.5 3.3 82.5 1 0 Ext.Wall 20 0.57 11.4 3.6 72 0.31 9 Int.Wall 45 1 45 3.6 162 0.62 1 Floor 75 2 150 4.3 322.5 0.59 2 Ceiling 75 2 150 6 450 0.46 3 (AU)=438.9 (AY)=1089 Table 2. Calculated Sol-Air Data Surface Lag(h) 24h teo 24h tao Time(h) teo Swing Ext.Wall 9 24.5 16.5 0700 15.5 -9 tao tao Window 0 - 16.5 1600 22 5.5 All figures in blue are calculated. Please refer to Appendix calculations. The solar radiance figures and solar gain coefficients come from CIBSE, 1986a, Table A8.1. On the basis of the above information derived from given statistics the peak environmental temperature is calculated as: Peak Environmental Temperature = C, where mean internal environmental temperature = C, and mean swing is () -=C. The peak environmental temperature is much above the upper limit of acceptability of internal environmental temperature at C. Though this acceptable temperature in itself is arbitrary as it does not take into account certain variables as an affected person's activity level, clothing, amount of direct solar irradiance on him or her, thermal insulation already available, and temperature and speed of air around further study has been done later to find a viable limit for the purpose of this investigation though all possible affecting variables shall be considered for that purpose. The purpose is to find three methods by which the existing peak environmental temperature within the building can be reduced below the recommended peak internal environmental temperature. Both calculated and recommended temperatures are for summer peak daily insolation period, Plymouth, Southeast England. Comfort Levels "Comfort is a state of mind" (Fergus Nicol. Sourced: Bordass, Bill). Thus, physiological models for human comfort are very hard to construct but certainly there is much scope for adaptive models in which respondents adapt to certain conditions. In this particular case thermal comfort to internal environmental conditions in a particular UK building is being considered. There are certain factors the interaction of which determines thermal comfort. They are as below: the climate, the building, its conditioning system (s), and its occupants. (A View from Northern Climes). Though, on consulting available literature on these more research has to be done, there is considerable evidence that if individual control such as dress etiquette is assigned to occupants they will tolerate more uncomfortable conditions which is particularly helpful in the case of naturally ventilated, such as the one under consideration, and hybrid buildings. Occupants will adapt to the building in relations to their expectations, clothing, posture, location and a bit of physiology. Nevertheless, increasing temperatures, especially in many parts of Europe with regular heat waves in summer, and more stressful working patterns, has placed limits to discomfort levels beyond which productivity will suffer. There will be increase in absenteeism, increase in ill health, loss of productivity, etc. (A View from Northern Climes) The increasing temperature that causes such discomfort itself is partly a product of the high-energy used to bring comfort levels within acceptable limits that feeds Cin the air aggravating the phenomenon of global warming. Also excessive usage of air-conditioning with constant feeding of Fluorocarbons into the atmosphere has its dangers in ozone layer depletion. With these concerns in mind the essay uses the following guidelines to find ways to bring down the high summer internal environmental temperature of the building to a suitably acceptable level. Only comfort is not being pursued. Adaptation and discomfort avoidance is also being considered. Passive and minimum-energy techniques are being considered to create a sound platform for a variety of activities. Systems being considered are energy-efficient with much consideration for hybrids and additional advice to avoid unnecessary utilisation of systems. Design intentions will be made clear to improve usability. All techniques shall be as simple as possible for better scope of understanding but not at the cost of efficiency. It is being believed that these sustainable solutions will be robust, adaptive and responsive but not fragile. (Bordass, Bill) Methodology The methodology applied to calculate the Peak environmental temperature is to first derive the mean temperature and the swing in temperature from peak to mean and add the two. For this purpose the following data figures are calculated: 1. 24 h mean solar heat gains 2. 24 h mean internal heat gains 3. Mean internal environmental temperature from the known heat gains and the mean external environmental temperature 4. Peak swing in heat gains above 24 h mean 5. Swing in environmental temperature because of swing in heat gains 6. Peak environmental temperature (the mean plus swing values) The two variables considered in calculating the heat gains are the people and the light bulbs. It is assumed that the building does not possess any large equipment that may generate any significant amount of heat. The irradiance figures and coefficients of glass and other materials and correlation factor figures are all derived from CIBSE, 1986a, Table A8.1 unless otherwise stated. It is agreed that cooling is essential for the subject building as peak internal environmental temperature ranges at C. An ASHRAE study into the value of cooling conducted on commercial US buildings finds that productivity peaks at 100 % within a temperature range of 24-C. Above C productivity continues to fall drastically (ADNOT, Jerome, P. 2). The strategy adopted to cool down the building is based on some facts. Firstly, it is assumed that the building is not constructed ecologically and it is not possible to refit it to the extent necessary to enable entirely natural methods of cooling. Thus, the strategy considers passive, hybrid and low-energy methods. The logic behind this is that another survey conducted by 'Building Use Studies, 2002' on UK buildings shows that productivity increases most when natural or hybrid systems are utilised to cool down buildings. Though total air conditioning is acknowledged as the most efficient method of cooling somehow the survey shows that natural ventilation and hybrid systems do much better than AC alone at increasing productivity and sustaining it at relatively high levels (Bordass, Bill, P. 9). Based on these findings the three following methods are being applied to decrease internal temperature. First Method: Low E Window Coating and Mechanised Ventilation The generic name for this technology is low solar gain low-e coating and it is applicable in hot climates. In this case it is being used to lower the internal environmental temperature of the building. The initial technology was introduced in the 80s to coat large sheets of glass in vacuum and the coatings were actually applied to the internal surface of the glass panes to prevent long-wave infrared waves from escaping out of the building. The utility of these coatings was to maintain internal temperatures at comfortable levels in cold climates. In the 90s this technology was adopted for cooling down buildings in hot climates. This adopted technology is being considered. How it Works The coating is a strongly spectrally selective one (Fenestration: How windows work). It blocks the long wave infrared waves in sunlight from entering into the building by reflecting them back outside. Nevertheless it allows light from the visible part of the spectrum to enter. Thus it appears clear without any tinting effect and the interior of the building is well lighted though less warm. It also blocks the shorter waved ultraviolet light from entering. The reason why the warmth is kept out is because more than half of the sun's energy in sunlight is carried by long wave infrared rays and if these are kept out the heat inside automatically diminishes. (Fenestration: How windows work). The visible transmittance is usually high for this type of coated glass being at 0.6 to 0.8 (60-80% visible light admittance). The other number is the solar heat gain coefficient (SHGE) that is low at 0.4 (40% admittance). (Fenestration: How windows work). The Mechanised Ventilation System: A supply ventilation system will be installed with fans to pressurise outside air into the building and distribute it through a duct system that allows the outside air into each room of the office. Intentional vents will be installed in each room through which the inside air will be forced outside by the pressure built up by the incoming outside air. The fan unit or units will be placed at a place outside the building, in a room on the roof probably, so that heat generated by the operation of the fan or fans do not affect the inside heat mechanism. Filters will be placed at the points of entry of outside air so that pollutants are not allowed in. In this particular case the ventilation system is geared to supply 4 air changes per hour to the whole building. (Whole-House Ventilation System, 2002) Calculations: Aside from the data presented at the beginning of the essay additional data used here: Solar heat gain coefficient of coating - 0.4 (Assumed that thermal transmittance of the glass used - 3.3 W/K, same as in table, with alternating solar gain factor at 0.2) Airflow by ventilation - 4 vol/h Mean solar gain = 185 W/.x 25 x 0.4 = 1850 W Mean internal gain = 430 W (Appendix 1) Total mean heat gain Q = 1850W + 430W = 2280 W Mean Gain Q = (AgUg) (tei-toa) + 0.33 NV (tei-tao) + (AfUf) (tei - teo) ..(1) Where, Heat gain by window area - (AgUg) = 82.5 W/K (Appendix 1) Heat gain by opaque fabric area - (AfUf) = 11.4 W/K (Appendix 1) Volume of building V - 225 (Appendix 1) Airflow - 4 vol/h (Ventilation) From Table 2: Mean tao = 16.5 Mean teo = 24.5 Putting the values in (1): 2280 = 82.5 (tei - 16.5) + 0.33 x 4 x 225 (tei - 16.5) + 11.4 (tei - 24. 5) 2280 = 82.5 tei - 1361.25 + 297 tei - 4900.5 + 11.4 tei - 279.3 2280 + 1361.25 + 4900.5 + 279.3 = (82.5 + 297 + 11.4) tei 8821.05 = 390.9 tei tei = C This is the mean internal environmental temperature and it is observable that it is a couple of degrees less than the one earlier had by using just glazed window glass. The swing from mean to peak in internal environmental temperature: Qi = [(AY) + 0.33NV ] Swing in solar irradiation gain - 2200 W (Appendix 2) Swing in S wall heat gain - 31.8 W (Appendix 2) Swing in glass conductance - 453.75 W (Appendix 2) Swing in ventilation - 0.33NVtao = 0.33 x 4 x 225 x 5.5 W = 1633.5 W Swing in internal gains = peak gains - mean gains = 860 W (Appendix 2) Total swing in gains Qi = (2200 - 31.8 + 453.75 + 1633.5 + 860) W = 5115.45 W From table 1 : (AY) = 1089 W/K Qi = [(AY) + 0.33 NV] 5115.45 = (1089 + 0.33 x 4 x 225) (Here = swing in temperature from mean to peak) 5115.45 = (1089 + 297) = 5115.45/1386 = C Therefore peak internal environmental temperature = C + C = C This is not quite the most efficient of cooling systems yet it lowers the temperature very close to the optimum range of 24-C as per the ASHRAE study to generate maximum productivity within the building. (ADNOT, Jerome, P. 2). The Second Method: Glazed Glass and Mechanised Ventilation The second method utilises the existing glazed glass windows and mechanised ventilation. The mechanised ventilation system is the same as that used in the first method with the same characteristics. Calculations: Mean solar gain = 1156.25 W (Appendix 1) Mean internal gain = 430 W (Appendix 1) Total mean heat gain = 1156.25 + 430 = 1586.25 W Mean Gain Q = (AgUg) (tei-toa) + 0.33 NV (tei-tao) + (AfUf) (tei - teo) ..(1) Gain through window area = 82.5 W/K (Appendix 1) Gain by opaque fabric = 11.4 W/K (Appendix 1) From Table 2: Mean tao = 16.5 Mean teo = 24.5 Air changes N = 4 vol/h Volume of the building = 225 1586.25 = 82.5(tei - 16.5) + 0.33 x 4 x 225(tei - 16.5) + 11.4(tei - 24.5) 1586.25 = 82.5tei - 1361.25 + 297tei - 4900.5 + 11.4tei - 279.3 1586.25 + 1361.25 + 4900.5 = 82.5tei + 297tei + 11.4tei 7848 = 390.9tei tei = C Since the same conditions apply for the derivation of the swing in temperature for the second method as the first, Swing = C (Same as in the first method) Therefore, Peak internal environmental temperature = C + C = C This temperature is also very close to the optimum range 24-C and though it is slightly less than at a level within the range it still is close enough to allow sufficient comfort. Third Method: Plain Glass, Sunscreens and Mechanised Ventilation In the third method the glazed window glass is changed for plain glass with sunscreens made of material capable of decreasing heat gains through the glass by 50 %. Also, in attendance, mechanised ventilation of the type used in methods one and two is applied. The power of the ventilation system is increased to 6 air volumes per hour to compensate the reduced capacity of the passive cooling device, the sunscreens. The following calculations will reveal the peak environmental that can be expected from this hybrid-cooling concept. Calculations: Mean solar heat gain by window area = 185 W/.x 25.x 0.5 = 2312.5 W Mean internal gain = 430 W (Appendix 1) Total mean heat gain = 2312.5 + 430 = 2742.5 W Mean Gain Q = (AgUg) (tei-toa) + 0.33 NV (tei-tao) + (AfUf) (tei - teo) ..(1) Gain through window area = 82.5 W/K (Appendix 1) Gain by opaque fabric = 11.4 W/K (Appendix 1) From Table 2: Mean tao = 16.5 Mean teo = 24.5 Air changes N = 6 vol/h Volume of the building = 225 2742.5 = 82.5(tei - 16.5) + 0.33 x 6 x 225(tei - 16.5) + 11.4(tei - 24.5) 2742.5 = 82.5tei - 1361.25 + 445.5tei - 7350.75 + 11.4tei - 279.3 2742.5 + 1361.25 + 7350.75 + 279.3 = (82.5 + 445.5 + 11.4)tei tei = 11733.8/539.4 = C This mean temperature is also within range of prescribed comfort margins. The calculations for the swing in temperature follows. The swing from mean to peak in internal environmental temperature: Qi = [ (AY) + 0.33NV ] Swing in solar irradiation gain - 2200 W (Appendix 2) Swing in S wall heat gain - 31.8 W (Appendix 2) Swing in glass conductance - 453.75 W (Appendix 2) Swing in ventilation - 0.33Nvtao (Where N = 6 and other figures remain constant as previously) = 0.33 x 6 x 225 x 5.5 W = 2450.25 W Swing in internal gains = peak gains - mean gains = 860 W (Appendix 2) Total swing in gains Qi = (2200 - 31.8 + 453.75 + 2450.25 + 860) W = 5964 W From table 1 : (AY) = 1089 W/K Qi = [(AY) + 0.33 NV] 5115.45 = (1089 + 0.33 x 6 x 225) (Here = swing in temperature from mean to peak) 5964 = (1089 + 445.5) = 5964/1534.5 = C Therefore, Peak environmental temperature = C + C = C This peak temperature also lies within the optimum range of 24-C. Concluding Discussion It is observable from the results that all three methods applied here are successful in reducing inside peak environmental temperature to within a prescribed optimal range. In the first method the combination of glass coating and mechanised ventilation is least successful in doing this while the third method that utilises sunscreens and mechanised ventilation is most successful. The third method utilises the most powerful ventilation device. The extra energy utilised to cool down the building is much less in all three cases as much of the cooling is done by passive methods - the coatings, glazing and sunscreens. It should be noted that natural ventilation is not utilised as the problems with reconstruction are many and have been avoided here. Also natural ventilation is not as powerful a method of cooling as mechanised ones. Nevertheless the essay notes that the three methods utilised are quite successful and energy efficient in lieu of the good work they do. Cooling has been administered at what is believed to be at optimal energy usage levels. It is to be noted that the first method is most preferred though it seems to be the least efficient. The ambient peak temperature is still within acceptable limits and the additional benefit of natural light filtering in through the window coating has a pleasant effect that goes beyond aesthetics as present psychology admits that natural lighting is the most preferred ambience. If necessary the power of the ventilation system may be increased beyond the level utilised here. Also, it should be noted that the cooling effect of the ventilation system may produce uncomfortably cold ambience in winter when the outside temperature falls. It is suggested that the ventilation system be used only in summer while, in winter, the existing natural ventilation that is available be made operational. This will not only save energy and costs but also maintain comfortable conditions within the building. It should also be noted that the fresh air supply per person per minute is well within the prescribed norms for all the additional ventilation systems applied within the scope of the essay. Reference A View from Northern Climes, Undated. Extracted on 26th February, 2006, from: http://www.iea.org/dbtw-wpd/Textbase/work/2004/cooling/Alan%20Young.pdf#search='The%20user%27s%20perspective%20A%20view%20from%20northern%20climes' ADNOT, Jerome, Undated, What is the Value of Cooling Extracted on 26th February, 2006, from: http://www.iea.org/dbtw-wpd/Textbase/work/2004/cooling/JeromeAdnot.pdf#search='What%20is%20the%20value%20of%20cooling%3F%3F%20Jerome%20ADNOT' Bordass, Bill, Comfort, Behavior, People and Energy, Undated. Extracted on 26th February, 2006, from: http://www.iea.org/dbtw-wpd/Textbase/work/2004/cooling/Bordass%20Comfort%20A3.pdf#search='Europrosper%20The%20user%27s%20perspective' CIBSE, 1986a, Table A8.1. Fenestration: How Windows Work, About Solar Gain, Undated. Extracted 22nd February, 2006, from: http://www.fsec.ucf.edu/bldg/active/fenestration/how/gaintutor.htm Whole-House Ventilation Systems, US Department of Energy's National Renewable Energy Laboratory, 2002. Extracted on 1st March, 2006, from: http://www.eere.energy.gov/buildings/documents/pdfs/26458.pdf#search='DOE%20Whole%20house%20ventilation%20systems' Bibliography Abushakra, Bass, et al, Compilation of Diversity Factors and Schedules for Energy and Cooling Load Calculations, ASHRAE Research Project 1093, 1999. Extracted on 22nd February, 2006, from: https://txspace.tamu.edu//handle/1969.1/2848 Chapter 10, Heat Loss Calculations, Undated. Extracted on 26th February, 2006, from: http://www2.fe.psu.edu/dxm15/aet121/Ch10HeatLoss.htm#Factors%20Affecting%20Comfort%20in Energy Cost and IAQ Performance of Ventilation Systems and Controls, US Environmental Protection Agency, Indoor Environments Division, 2000. Extracted on 26th February, 2006, from: http://www.epa.gov/docs/iaq/largebldgs/resources/(2)%20Energy%20Cost%20and%20IAQ/Project%20Report%203.PDF#search='EPA%20Ventilation%20systems%20and%20controls%20Project%20Report%203' Gordon, David, Shedding light on solar gain and glare, 2001. Extracted on 26th February, 2006, from: http://www.fmb.org.uk/publications/masterbuilder/july01/19.asp#top Graham, Carl Ian, High-Performance HVAC, 2005. Extracted on 26th February, 2006, from: http://www.wbdg.org/design/hvac.phpprint=1 Holmes, Michael, Hybrid Ventilation Systems, Undated. Extracted on 26th February, 2006, from: http://www.caed.asu.edu/msenergy/Neeraj/Holmes.pdf#search='Hybrid%20ventilation%20Systems%20Michael%20Holmes' Potter, I.N., Air Tightness Specifications, 1998. Extracted on 22nd February, 2006, from: http://www.bsria.co.uk/bookshop/sample/S10-98.pdf#search='Air%20tightness%20specifications%20I.%20N.%20Potter' Shading: First Step Toward Natural Cooling, Green Building Source, 1994. Extracted on 22nd February, 2006, from: http://oikos.com/esb/34/shading.html#trees Sherman, M.H., ASHRAE's Residential Ventilation Standard: Exegesis of Proposed Standard 62.2, 1999. Extracted on 26th February, 2006, from: http://www-epb.lbl.gov/EPB/Publications/lbnl-42975.pdf#search='WholeHouse%20ventilation%20ystems' Appendix 1. Standard Calculations: Standard calculations involved in calculating the peak internal environmental temperature of the building in peak summertime in Plymouth, Southeast England. Table 1: Heat Transfer data. Surface A(m) U(W/m)K AU Y(W/mK) AY Lag(h) Glass 25 3.3 82.5 3.3 82.5 1 0 Ext.Wall 20 0.57 11.4 3.6 72 0.31 9 Int.Wall 45 1 45 3.6 162 0.62 1 Floor 75 2 150 4.3 322.5 0.59 2 Ceiling 75 2 150 6 450 0.46 3 (AU)=438.9 (AY)=1089 A = Area U = Thermal Transmittance Y = Swing Values f = Correlation factors Table 2: Sol-air data Surface Lag(h) 24h teo 24h tao Time(h) teo Swing Ext.Wall 9 24.5 16.5 0700 15.5 -9 tao tao Window 0 - 16.5 1600 22 5.5 Peak solar radiance on a west-facing window at 1600 hrs on 21st June in Southeast England - 625 W/ Daily mean solar radiance at same time on same day - 185 W/. Mean solar gain coefficient for the window glazing without blinds - 0.25 Alternating factor for the mean to peak solar gain - 0.2 Mean Gain Q = (AgUg) (tei-toa) + 0.33 NV (tei-tao) + (AfUf)) (tei - teo) Where, Af = Area of opaque fabric (m) Ag = Area of window (m) Uf = Thermal transmittance of opaque fabric (W/mrK) Ug = Thermal transmittance of window (W/mK) tei = Mean internal environmental temperature (C) teo = Mean external environmental temperature (C) tao = Mean external air temperature (C) The solar radiance figures and solar gain coefficients come from CIBSE, 1986a, Table A8.1. Calculation of the 24 h mean environmental temperature: 1. Mean solar gain by windows - (Daily mean irradiance) x (Total window area) x (solar gain coefficient) = 185 W/.x 25.x 0.25 = 1156.25 W 2. Mean internal gain from people and equipment - [(Gain from 6 people for 8 h) + (Gain from 5 light bulbs for 8 h)]/24 h = [ (6 x 90W x 8h) + (5 x 150W x 8h)]/24h = 430 W Total internal mean gain Q = Gain by windows + Gain from people and equipment = 1156.25 + 430 = 1586.25 W Also, Mean gain Q = (AgUg) (tei-toa) + 0.33 NV (tei-tao) + (AfUf) (tei - teo) Gain through window area = (AgUg) = 25mx 3.3 W/mK = 82.5 W/K Gain by opaque fabric = (AfUf) = 20m x 0.57 W/mK Where, Af (Area of fabric) = Area of wall - Area of windows = (15 x 3) - 25 = 20 = 11.4 W/K Air changes = 1.5 vol/h Volume of building V = (15 x 5 x 3)m = 225 Putting derived values and appropriate constants from the tables in the following equation, Q = (AgUg) (tei-toa) + 0.33 NV (tei-tao) + (AfUf) (tei - teo) 1586.25 = 82.5(tei - 16.5) + 0.33 x 1.5 x 225(tei - 16.5) + 11.4(tei - 24.5) 1586.25 = 82.5tei - 1361.25 +111.375tei - 1837.69 + 11.4tei - 279.3 1586.25 + 1361.25 + 1837.69 + 279.3 = (82.5 + 111.375 + 11.4)tei 5064.49 = 205.275tei tei = C (Mean internal environmental temperature) The swing, mean to peak, in the internal environmental temperature is calculated as below: Qi = [ (AY) + 0.33NV ] where Qi is the total swing in heat gains 1. Swing in solar radiation gain through windows: (Alternating solar gain factor for glass) x (Peak solar irradiance - Mean solar irradiance) x Total window area. 0.2(625 W/ - 185 W/) x 25. = 2200 W 2. Swing in S wall heat gain = fAUteo = 0.31 x 20 x 0.57 W/K x (-9)K = -31.8 W Swing in glass conductance = fAUtao = 1 x 25x 3.3 W/K x 5.5K = 453.75 W Swing in ventilation = 0.33Nvtao = 0.33 x 1.5 x 225 x 5.5 W = 612.56 W Swing in internal gains = (Peak gains - Mean gains) = (Heat gain by 6 people) + (Heat gain by 5 light bulbs) - Mean internal gains = [(5 x 90) + (5 x 150) - 430] W = 860 W Therefore, Qi = (2200 - 31.8 + 453.75 + 612.56 + 860) W = 4094.51 W From Table 1: (AY) = 1089 W/K Qi = [(AY) + 0.33 NV] Therefore, putting the values, 4094.51 = [1089 + 0.33 x 1.5 x 225] = 4094.51/1200.375 = C This is the swing in temperature from peak to mean. Therefore peak temperature = Mean temperature + Swing in temperature = C + C = C Read More