environmental house project jack bradley
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Environmental house project Jack Bradley. What will be covered in this lecture?. Why people need a house How technology provides a house Design skills. How many types of house can you name?. Traditional Houses. Yurt (2) Igloo (3) Grass House (4) Pueblo. - PowerPoint PPT PresentationTRANSCRIPT
What will be covered in this lecture?
(1) Why people need a house
(2) How technology provides a house
(3) Design skills
Reasons for diversity
Reasons
For
Diversity
Materials
Climate
Ways of Life
TechnologyEconomics
Socio – cultural factors
Wood – Its properties
(1) Resists tensile and compressive forces
(2) Easy to work with simple tools
(3) Light and easy to manipulate
(4) Good thermal insulator
(5) Spans distances
(6) Feels warm
Orientation
• Wind/weather
• Sun – overheating V natural heat
• Topography – drainage, stream use, shelter
• Natural shading – trees – summer/winter (deciduous)
Green/Sustainable Building
Definitions:
To be classed as a green building it is
“…essential for the environmental impact of all its constituent parts and design decisions to be evaluated.”
“ A healthy built environment based on resource efficient and ecological principles.”
Design Principles
• Reduce energy in use
• Minimising external pollution and external damage
• Design in harmonious relationship with surrounds
• Avoid destruction of natural habitats
• Re-use rainwater
• Treat and recycle waste water
• Minimise extraction of materials
• Minimise waste materials provided (typically 10%)
Green design
• Solar Collector
• Rainwater Cistern
• Conservatory
• Earth heat storage bed
• Power generation (wind, water etc)
• Waste recycling system
• Insulation
• Renewable materials
Example
Sketch a graph of temperature against time for a house where the heating pattern is as follows. The heating is turned on at 6am and off at 11am. It is turned on again at pm and off again at 11pm. When the heating is on, the occupants require the temperature to be 23C. On your graph, indicate the approximate values of the average inside temperature.
Heating a house
Heat Flow Rate = U-Value * Area temperature difference
Ventilation loss = Specific heat capacity * Mass flow rate of air * Temperature difference
Mass flow rate of air =
Air change rate * House Volume * density of air
3600
Equation
Ventilation Loss =
0.33 x House Volume x Air change rate x Temperature difference.
Average temperature and degree-days
Total heat required = Specific loss * degree days * 86400
Example 2
Calculate the rate of heat loss from the house shown below when the temperature difference between the inside and the outside is 20C. The house has an air change rate of 1.0ach, walls with U-values of 0.6Wm-² C-1 and U-values of 0.3Wm-² C-1 for the roof, 0.8 for the floor, 3.4 for doors and 5.6 for the windows. The total area of window is 12m² and there is 4m² of external doors
6m6m
5.5m
Solution 2
Total wall area = 4 x 5.5m x 6m =132m²
Net wall area = total wall area – window area – door area
=132m² - 12m² - 4m² =116m²
Floor area = 6m x 6m = 36m²
Roof area = 6m x 6m = 36m²
House volume = 5.5m x 6m x 6m = 198m²
Fabric loss = U-Value x area x temp. difference
For walls: fabric loss = 0.6 x 116 x 20W = 1392W
For the floor: fabric loss = 0.8 x 36 x 20W = 576W
For the roof: fabric loss = 0.3 x 36 x 20W = 216W
For the windows: fabric loss = 5.6 x 12 x 20W = 1344W
For the doors: fabric loss = 3.4 x 4 x 20W = 272W
Total fabric loss = 1392W + 576W + 216W + 1344W + 272W = 3800W
Ventilation loss = 0.33 x house volume x air change rate x temp. difference
= 0.33 x 198 x 1 x 20W = 1306.8W
Total rate of heat loss = fabric loss + ventilation loss = 3800W + 1306W = 5106.8W
Specific loss = total rate of heat loss
temperature difference
5106.8 = 255.34 W
20 C
Internal and Solar gains
In a typical house, the total gains from all sources will be about 1000W.
Te specific loss will approximate to 255W C^-1
Temperature rise from internal & solar gains = Total gains / Specific loss
Region Degree Days Region Degree Days
Home Countries 2137 Northumberland 2727
Southeast 2445 North Yorkshire 2534
South 2286 South Yorkshire 2398
Southwest 1966 East Anglia 2468
Severn Valley 2235 West Scotland 2615
West Midlands 2527 East Scotland 2744
Merseyside 2389 North Scotland 2903
Cumbria 2556 Wales 2276