Essay: Controlling Heat Gain In A Bungalow During Summer - Sources, Mechanisms, And Calculations.

Floor plan of the case study dwelling (bungalow) along with all the dimensions that you need are given in the appendix. All windows are manually controlled by the occupants. All windows are 6 mm hard coat low emissivity double glazing with internal blinds. None of the doors has any glazing. There is no external shading.

1. Identify potential sources of heat gain during summer and their likely operation/occupancy profile in each room. This should include a list of typical equipment that can be found in a home. Discuss different mechanisms of heat transfer for each source.
2. For each room calculate internal casual gains per unit floor area from equipment,people and lighting that you identified in You should use method b (detailed method) discussed in section 5.2 of CIBSE TM37 (2006) and state any assumptionsthat you make and any formula that you use. You should also provide references for
the values that you use in your calculations.
3. For each room calculate solar gains (solar load) per unit floor area for a peak summer day* for three different locations: a) Edinburgh b) Manchester c) London. Calculating solar gains are explained in section.

Sources of Heat Gain During Summer and Their Likely Operation/ Occupancy Profile in Each Room

The gain of heart is considered to be a real challenge during summer in the places that experiences hot temperature. The challenge is experienced in the periods when attempts are made to ensure that there is reduction of the temperature and subsequent introduction of the cooling effects. This is common when one tries to reduce the temperature without the use of the conditioners .However; there are five potential sources that can easily be controlled in the best ways possible(Klõšeiko, Arumägi and Kalamees 2015).

Appliances and electronics

Most of the home appliances that are placed in the open places normally have shiny finishing. Some of these appliances include the following: Washing machines. Ovens, radios and dishwashers. These appliances are known to generate considerable amount of heat during the process of their use. The heat is transferred from these appliances through the convection and radiation process. In some cases, the transfer of the heat can be achieved through conduction(Serghides  and Georgakis 2012).

In order to minimize the effects of the heat gain from these appliances. The following activities or the prevention measures can be adopted. The appliances can be used only in the evening when the temperatures have gone down. There appliances like the computers can actually be shut down when they are not in use. There should be attempt to ensure that free circulation of the cool air is allowed whenever such equipment are in use(Stevens 2013).

Windows

The UV rays normally enter the room by the use of the windows before they finally get trapped inside the building. This normally leads to the rise of the temperature of the room at a faster rate. The heating effect is achieved by the means of the rising convectional current. The effects of such events can be controlled by closing of the blinds and also the drapes in the course of the daylight periods.

Walls

It is a common phenomenon that the walls of the buildings are normally exposed to the rays of the sunlight. The walls normally facilitate the heat transfer through the radiation effects. In order to ensure that the heat gain through the radiations from the walls of the building are controlled, the walls should be painted white .White colors are known for effective reflection of the heat that are excess hence causing the cooling effects. Also the ceramic coatings can be used to help in the regulation of the heat gain.

Leaks

The cracks that are common on the walls of the building have served as the passage for the convection currents. Such cracks are found around other places like the door frames, jams of the door and also other fixtures. Normally such places allow for the escape of the cool air from the building through the processes of convection and radiation. In order to control similar effects, the doors should never be left open .Also the windows should be closed most of the time(Perez et al 2012).

Ceilings and Attics

The ceiling of the buildings normally get heated as long as the attics also get heated. The room becomes heated through the process of the convection. This basically means that the heating can only be controlled by ensuring that there is proper ventilation and also insulation of the between the ceilings and the attic. The ceiling materials that re used should have the higher R-value so as to assist in minimizing the effects.

Appliances and Electronics

 Wall structure heat gain

In this particular part, the calculations involving the heat gains in the room have been summarized in the table form.

Room	Area of the room (m2)	Capacity of the room per person	Quantity of the windows and doors	Quantity of the escalators	Required number of fans
F-6	97.94	60-70	10	4	4
F-7	97.94	60-70	6	4	4
F-14	112.05	60-70	6	4	4
F-15	104.17	60-70	6	4	4
F-16	104.17	60-70	8	4	4
F-18	119.85	60-70	10	4	4
F-22	83.42	60-70	9	4	4

Heat gain through the glass windows

Heat gain through appliances

Heat gain from fluorescents

= Watts of fluorescents x 1.25 x No. of fluorescents

= 40x1.25x28 = 1400 W

Where, 1.25 is factor considering the heat gain from choke. Heat gain from fans

= Watts of Fan x No. of Fans

= 60x28 = 1680 W

Total heat gain from Appliances (fluorescents and fans):

= 3080 W

Gain of heat from the occupancy

Persons per room taken on average as =66

Number of the rooms=7

Period of the occupancy=7hrs

Overall number of people=7*66=462

Metabolic rate at 25 degrees from individual =70W

Latent heat=45W

Total latent heat=45*462=20790W

Total heat gained from occupancy=53130W.

Infiltration from the leaks

Size of the door=2.83*1.524m2

Quantity of doors per room=1

Velocity of the room=12km/hr.

In order to calculate the gain of the heat that takes place through the doors, the volume taken by an individual per minute

m3/ min/ person = 0.09912

Area of the door = 4.313 m2

From psychometric chart

At 25°C and 50% RH, hi = 51.00 kJ/kg of air

Sensible heat gain (S.H.G) mi= (hk  - hi )

= 0.001836 x 13 = 23.86 W

Latent heat gain (L.H.G) ( mi  = ho   - hk  

= 0.001836 x 16.1 = 29.56 W

Total sensible heat gain (T.S.H.G) = 462 x 23.86

= 11023.32 W

Total latent heat gain (T.L.H.G) = 462 x 29.56

= 13656.72 W

Total heat gain (T.H.G) = 24680.04 W Infiltration through window:

Area of window =Aw =2.178 m2

At 12 km/hr(200 m/min) average velocity of wind.

From table

m3/min m2 = 0.067

m3/min (for 1 window) = 0.067x 2.178 = 0.146 m3/min. Mass flow rate due to infiltration through window (miw )

= 0.146 / 0.90 = 0.162 kg/min miw =0.0027023 kg/sec

Total number of window = 55

Total number of persons = 462

Sensible heat gain / window = miw ; hk   - hi 

= 0.0027023x 13 x 1000 = 35.13 W

Latent heat gain /window; miw =ho  -hk 

= 0.0027023x 16.1 x 1000 = 43.51 W Total sensible heat gain (T.S.H.G)

= 462 x 35.13 = 16230.06 W Total latent heat gain (T.L.H.G)

= 462 x 43.51 = 20101.62 W

Total heat gain (T.H.G) = (T.S.H.G) + (T.L.H.G)

= 36331.68 W

Edinburgh

Calculation of the Heat Gain per floor area.

Internal conditions : 25o C dry bulb, 50 percent RH

External conditions : 43o C dry bulb, 24o C wet bulb

U-value for wall : 1.78 W/m2 .K

 U-value for roof : 1.316 W/m2 .K

U-value for floor : 1.2 W/m2 .K

Effective Temp. Difference (ETD) for wall: 25o C

Effective Temp. Difference (ETD) for roof: 30o C

U-value for glass ; 3.12 W/m2 .K

Solar Heat Gain (SHG) of glass ; 300 W/m2

 Internal Shading Coefficient (SC) of glass: 0.86

 Occupancy : 4 (90 W sensible heat/person) (40 W latent heat/person)

Lighting load : 33 W/m2 of floor area

Appliance load : 600 W (Sensible) + 300 W(latent)

 Infiltration : 0.5

Changes in  per Hour Barometric pressure : 101 kPa

For the internal conditions of 25o C dry bulb, 50 percent

 RH: Wi = 9,9167 x 10-3 kgw/kgda

 For the external conditions of 43o C dry bulb, 24o C

wet bulb: Wo = 0.0107 kgw/kgda,

Density of dry air = 1.095 kg/m3

Total value becomes= 15956 W

This value will be applicable for London as well considering the temperature variation is the same.

Manchester

Configuration or varied orientation

 External loads:

• Transfer of heat rates via walls:

Considering that only west wall measuring 3m x 3m with glass windows of 1.5m x 1.5m is exposed; the heat transfer rate through this wall is given by:

Qwall = UwallAwallETDwall = 1.78 x (9-2.25) x 25 = 300.38 W.

1. b) Heat transfer rate through roof:

 Qroof = UroofAroofETDroof = 1.316 x 18 x 30 = 710.6 W.

1. c) Heat rate transfer via the floor:

Considering that the building stands on a well-established, it can be assumed the conditions in the basement to be same as that of the outside (i.e., 43o C dry bulb and 24o C wet bulb), since the floor is not exposed to solar radiation, the driving temperature difference for the roof is the temperature difference between the outdoor and indoor, hence: Qfloor = UfloorAfloorETDfloor = 1.2 x 18 x 18 = 388.8 W .

• Heat transfer rate in the SW orientation:

Windows

This consists of the radiative as well as conductive components. Since no information is available on the value of CLF, it is taken as 1.0. Hence the total heat transfer rate through the glass window is given by: Qglass = Aglass [Uglass(To−Ti)+SHGFmaxSC] = 2.25[3.12 x 18 + 300 x 0.86] = 706.9 W (Sensible) e) Heat transfer due to infiltration: The infiltration rate is 0.5 ACH, converting this into mass flow rate, the infiltration rate in kg/s is given by: minf = density of air x (ACH x volume of the room)/3600 = 1.095 x (0.5 x 3x3x6)/3600 minf = 8.2125 x 10-3 kg/s

Sensible heat transfer rate due to infiltration,Qs,inf; Qs,inf = minfcpm(To−Ti) = 8.2125 x 10-3 x 1021.6 x (43 – 25) = 151 W . Latent heat transfer rate due to infiltration, Ql,inf: Ql,inf = minfhfg(Wo−Wi) = 8.8125x10-3 x 2501x103 (0.0107−0.0099)=16.4 W.

1. b) Load due to SE orientation: The sensible and latent load due to occupants are: Qs,occ = no.of occupants x SHG = 4 x 90 = 360 W Ql,occ = no.of occupants x LHG = 4 x 40 = 160 W b) Load due to lighting: Assuming a CLF value of 1.0, the load due to lighting is: Qlights = 33 x floor area = 33 x 18 = 594 W (Sensible)
2. c) Load due NW orientation: Qs,app = 600 W (Sensible) Ql,app = 300 W (Latent)

Total sensible and latent loads are obtained by summing-up all the sensible and latent load components (both external as well as internal) as: Qs,total = 300.38+710.6+388.8+706.9+151+360+594+600 = 3811.68 W Ql,total = 16.4+160+300 = 476.4 W.

(d) Total load on the building is for NE orientation:

 Qtotal = Qs,total + Ql,total = 3811.68 + 476.4 = 4288.08 W  Room Sensible Heat Factor (RSHF) is given by: RSHF = Qs,total/Qtotal = 3811.68/4288.08 = 0.889. To calculate the required cooling capacity, one has to know the losses in return air ducts(Sailor, Elley and Gibson 2012). Ventilation may be ignored as the infiltration can take care of the small ventilation requirement. Hence using a safety factor of 1.25, the required cooling capacity is: Required cooling capacity = 4288.08 x 1.25 = 5360.1 W ≈ 1.5 TR hence the best orientation.

Lightweight Vs Heavyweight Construction materials

In the summer seasons, there is need to control the heat gain effects even from the construction. This can be achieved through integration of various types of the design of the structures and materials used. This however depends on the predisposed factors that will finally impact the product(Hens 2017). The use of the products of aluminum in the making of the roof instead of the timber will lead to the reduction of the weight of the structure. Aluminium structures reflect much heat as compared to timber that absorbs heat and add weight as well.

When Expanded Polystyrene that is commonly known as EPS is used in the wall masonry instead of using concrete for partitioning, the resultant structure will have light weight. The application of the EPS normally requires the use of the shortcreting on both sides although this activity makes the material use very expensive. Carbon fiber is generally another development material in the business however it turns out to be a treasure waiting to be discovered and ideally time will uncover how powerful and adaptable it very well may be over the long haul.

 Corrugated iron sheets or Decra material tiles are additionally successful in accomplishing light weight structure when contrasted with shingles and dirt material tiles.

 They are additionally more savvy (moderately shabby upkeep cost) and tough. Suspension connect with tensioned links is clearly lighter than a bracket connect with welded bars which thusly is lighter than a case support connect made of cement(Pavlík, Žumár, Pavlíková and ?erný 2012).  Aluminum entryway and window outlines are light load in contrast with steel outlines. The thing that matters isn't much yet at the same time tallies.  3D printing (added substance producing) is another idea in the development business.

Walls

3D printing can utilize distinctive sorts of crude materials for printing of which a portion of this materials will result in a light weight structures. Being generally new, the potential outcomes with 3D printing are relatively boundless. This is a zone which needs concentrated and further research on. Bamboo can be utilized rather than timber and still accomplish the ideal target and in the meantime bearing an a lot heavier load and it being a light weight material.

 Bamboo a be utilized rather than steel as support, however this should be looked into further since it might require a thicker solid cover henceforth may increment of level up the dead load of the structure.

From the precedents above, there are a lot of materials one can use to accomplish plume weight structures however for the majority of them to be in participated adequately into a building a great deal should be considered. Cost being one of them. Workmanship (experienced) is likewise fundamental in the accomplishing an ideal result which must be stylishly pleasing(Nelson, Hart, Zhou and Ozoli?š 2013). Durability is additionally an essential point to be considered. Expectation that answers your inquiry. There are no restrictions, not by any means the sky and there is just the same old thing new under the sun!

Thermal comfort refers to the state of mind that actually expresses ones satisfaction with the thermal environment. The thermal comfort is more than just known pleasant conditions. It should be considered part of the survival behaviour. The following approaches can be used in the thermal comfort

Draught control

The vibe of draught relies upon air temperature, air development and air choppiness. The human body can't detect the genuine air developments at low speed; however it can feel the expanded cooling of the skin, which is caused by the air developments (Derluyn et al 2013). If not satisfactorily kept up VELUX rooftop windows can be a wellspring of draught. More established rooftop windows with a harmed gasket can be defective and given chilly air access to a room in winter. So visit upkeep is expected to keep the window in a decent condition.

Old and vast sheets may cause downdraught from the windows, where a chilly inside sheet temperature cools the air and causes a descending air development. New low energy sheets are normally preferred for the reduction of the draught effect.

Radiant temperature symmetry

This Phenomenon can best be compared to an individual confronting a chimney on a chilly night. One side of the individual feels warm, alternate feels chilly, despite the fact that the air temperature is the equivalent. The distinction in warm sensation is caused by the distinction in brilliant temperature between the chimney and the cool environment(Yuan,  Emura and Farnham 2015)t. Brilliant temperature asymmetry can be found in two circumstances with VELUX items:

In winter, when within sheet temperature is extremely chilly because of the higher warmth misfortune contrasted with the dividers. Be that as it may, similarly as with draft, new windows will once in a while cause issues. An inward visually impaired or outer screen or canopy visually impaired can decrease or dispose of the hazard .In summer seasons when the occupants of the building becomes exposed to the direct sunlight, the solar shading methods can be applied as a means of eliminating the discomfort of direct sunlight.

Calculation of Day Light Factors

Taking the dimensions of the room to be 5.0mx4.0mx2.4m and also considering one 2.4mx1.3m double wall-glazed window, the calculation is done as follows. It is also assumed that the building color is very light and hence no obstruction.

Average DF =

Window area = 2.4 × 1.3 = 3.12 m²  

W = 3.12 × 0.7 = 2.18 m²  

T = 0.6 (approx.) for double-glazed windows in clean environment

θ = 73º

A = 2 × (5.0 × 2.4 + 4.0 × 2.4) + 5.0 × 4.0 + 5.0 × 4.0 = 83.2 m²  

R = 0.6 (considering light coloured room surfaces)

References

Delgado, J.M., Barreira, E., Ramos, N.M. and de Freitas, V.P., 2012. Hygrothermal numerical simulation tools applied to building physics. Springer Science & Business Media.

Derluyn, H., Griffa, M., Mannes, D., Jerjen, I., Dewanckele, J., Vontobel, P., Sheppard, A., Derome, D., Cnudde, V., Lehmann, E. and Carmeliet, J., 2013. Characterizing saline uptake and salt distributions in porous limestone with neutron radiography and X-ray micro-tomography. Journal of building physics, 36(4), pp.353-374.

Hens, H.S., 2017. Building physics-heat, air and moisture: fundamentals and engineering methods with examples and exercises. John Wiley & Sons.

Klõšeiko, P., Arumägi, E. and Kalamees, T., 2015. Hygrothermal performance of internally insulated brick wall in cold climate: A case study in a historical school building. Journal of Building Physics, 38(5), pp.444-464.

Nelson, L.J., Hart, G.L., Zhou, F. and Ozoli?š, V., 2013. Compressive sensing as a paradigm for building physics models. Physical Review B, 87(3), p.035125.

Palem, K. and Lingamneni, A., 2013. Ten years of building broken chips: The physics and engineering of inexact computing. ACM Transactions on Embedded Computing Systems (TECS), 12(2s), p.87.

Pavlík, Z., Žumár, J., Pavlíková, M. and ?erný, R., 2012. A Boltzmann transformation method for investigation of water vapor transport in building materials. Journal of Building Physics, 35(3), pp.213-223.

Perez?Alonso, F.J., McCarthy, D.N., Nierhoff, A., Hernandez?Fernandez, P., Strebel, C., Stephens, I.E., Nielsen, J.H. and Chorkendorff, I., 2012. The effect of size on the oxygen electroreduction activity of mass?selected platinum nanoparticles. Angewandte Chemie, 124(19), pp.4719-4721.

Sailor, D.J., Elley, T.B. and Gibson, M., 2012. Exploring the building energy impacts of green roof design decisions–a modeling study of buildings in four distinct climates. Journal of Building Physics, 35(4), pp.372-391.

Serghides, D.K. and Georgakis, C.G., 2012. The building envelope of Mediterranean houses: Optimization of mass and insulation. Journal of Building Physics, 36(1), pp.83-98.

Stevens, W.R., 2013. Building Physics: Lighting: Seeing in the Artificial Environment. Elsevier.

Yuan, J., Emura, K. and Farnham, C., 2015. A method to measure retro-reflectance and durability of retro-reflective materials for building outer walls. Journal of Building Physics, 38(6), pp.500-516.