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

Traditional Houses (5) Tepee (6) Trullo (7) Forest Pavillion (8) Mandan lodge

Traditional Houses (9) Bedouin tent (10) English Cottage

Jack and Joanne have moved again!

Reasons for diversity Materials Socio – cultural factors Climate Ways of Life Economics Technology

Why people need a house? Physical comfort Domestic activities Socio – cultural factors

What does technology provide? Materials Services Construction

Wood – Its properties Resists tensile and compressive forces Easy to work with simple tools Light and easy to manipulate Good thermal insulator Spans distances Feels warm

Influence of Services Gas Heating Drainage Electricity Hot water Cold water

Design Skills Required Analysis Synthesis Evaluation

Keeping Warm Location Orientation Shape

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

0.33 x House Volume x Air change rate x Temperature difference. 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 5.5m 6m 6m

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 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

Building activity relationship charts