Environmental house projectEnvironmental house project

Jack BradleyJack Bradley

What will be covered in this lecture?

(1) Why people need a house

(2) How technology provides a house

(3) Design skills

How many types of house can you name?

Traditional Houses

(1) 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

Reasons

For

Diversity

Materials

Climate

Ways of Life

TechnologyEconomics

Socio – cultural factors

Why people need a house?

(1) Physical comfort

(2) Domestic activities

(3) Socio – cultural factors

What does technology provide?

(1) Materials

(2) Services

(3) Construction

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

Influence of Services

(1) Gas

(2) Heating

(3) Drainage

(4) Electricity

(5) Hot water

(6) Cold water

Design Skills Required

(1) Analysis

(2) Synthesis

(3) Evaluation

Keeping Warm

(1) Location

(2) Orientation

(3) 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

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

Building activity relationship charts