ECONOMIC & ENERGY OF BUILDINGS IN THE TROPICS February 2015 Puducherry, India

Transcription

1 EXPERT GROUP MEETING ECONOMIC & ENERGY EFFICIENCY OF BUILDINGS IN THE TROPICS February 2015 Puducherry, India

2 Rahula Attalage Deputy Vice Chancellor / Senior Professor & Narein Perera Chartered Architect / Senior Lecturer University of Moratuwa Sri Lanka Energy efficient (green/ecological) residential housing: presentation of innovative projects and case studies ASiL Sri Lankan Perspective 2 nd February 2015

3 Halbarawaththa Housing Project, Mulleriyawa, Sri Lanka Thermal Comfort & Climate Analysis of Settlement Study done by Rohinton Emmanuel & Narein Perera. April, 2012

4 Thermal comfort in the tropics Settlement level Layout (especially street orientation) Street level features (building clusters, setbacks,...) Landscape control (trees, green yards) GOAL: Street-level t l shading & wind movement Building level House form (square, L Shape, courtyard) Orientation Design features (materials, color, texture...) GOAL: Solar radiation prevention & ventilation

5 Settlement-level level Analysis Parameters: 1. Orientation * N/S * NE/SW *NW/SE * NW/SE 2. Landscape features * Street trees * Soft street paving

6 Modeling ENVI-met * Grid pattern for input to ENVI-met * Layout of buildings

7 Model representation base case Simplified & gridded representation of layout and landscape

8 Settlement analysis At the level of whole development Compare temperature distribution Compare thermal comfort variations Analysis of specific locations Explore temperature and thermal comfort variations at representative locations within the development Suggest improvements Suggest improvements In terms of density, layout and green features

9 Settlement analysis Temperature distribution N th/n th t f d l p ti th t North/Northwestern corner of development is the warmest; Northern half being warmer could be due to selected date of simulation (April) Northwest needs improvement Pot. Temp = Potential Temperature in Kelvin. (i.e. deduct 273 to derive o C)

10 Settlement analysis Thermal comfort Little variation throughout h t the development; Streets are much warmer ( deg. C) than the plots MRT = Mean Radiant Temperature (is a measure of thermal comfort)

11 Effect of high density temperature More than 1 deg. C drop in temperature in most places; A small patch in the NW corner remains problematic

12 Effect of high density comfort Slight reduction and overall improvement in comfort Streets still remain problematic

13 Effect of greenery temperature Nearly no effect in temperature

14 Effect of greenery comfort Some improvement in street level MRT

15 Combined effect of greenery & density Best overall improvement, although not very significant

16 Thermal Comfort at specific points Receptor 03 Receptor 05 Receptor 02 Receptor 01 Receptor 04 Receptor Points

17 Thermal Comfort at R1 Tmrtbc Tmrtdc Tmrtgc Tmrtdgc :00:00 04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00:00 Greenery and density causes quicker cooling than the base case

18 Thermal Comfort at R2 Tmrtbc Tmrtdc Tmrtgc Tmrtdgc OMFORT THERMAL C :00:00 04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00:00 Greenery and density causes quicker cooling than the base case

19 340 Thermal Comfort at R5 Tmrtbc Tmrtdc Tmrtgc Tmrtdgc :00:00 04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00:00 Greenery and density causes slower warming than the base case. No R3 & R4

20 Comments on the final layout

21 Planning approaches Density increased Likely to be most beneficial Greenery Street level comfort likely to be best is street trees could be introduced/increased d/i d Combination of high density and greenery likely to be the most beneficial

22 Suggestions for improvement Northwest remains problematic Introduction of green belt / ponds likely to be useful Shading the streets (by buildings and / or trees) will improve year-round thermal comfort at settlement level Additional improvements to comfort should be attempted at building scale Orient buildings with longer sides facing North / south Shade individual buildings with trees Roof colour (light) and insulation i most likely l to be beneficial i

23 Ranawiru Gammanaya Ipalogama, Anuradhapura, Sri Lanka Thermal Comfort & Climate Analysis of Settlement Study by Rohinton Emmanuel, 2006

24 Located in the dry zone of north central Sri Lanka. The primary climatic issues are the excessive heat and the relatively dry (by Sri Lankan standards) conditions made worse by weak winds. Tasks / Objectives Estimate the thermal comfort of the proposed housing options; Estimate the outdoor climate (air temperature) of common areas that result from the different street orientations; i Propose design strategies to improve outdoor conditions by way of street orientation and housing layout; Propose building design strategies to improve indoor climate and comfort in terms of orientation, materials, roof cover and outdoor color.

25 I. Neighbourhood Model Street canyon is oriented northeast-southwest while houses are coupled and staggered (i.e. front and backyard width vary alternatively). Property lines too, are staggered. Typical schematic layout of dwelling units ENVI-met representation of a typical dwelling layout 25

26 The settlement-level climate and comfort simulation reveals the following: Northeast Southwest street orientation is better, especially when the houses are staggered North South street orientation is the worst orientation Encourage at least one medium size tree (crown dia. = 10m) in each front yard Wind speeds around buildings were similar even when buildings were not aligned equidistance from street line Encourage backyards to be as green as practical 26

27 ii. Building Model The building level simulation in DEROB LTH assumes; 9m wide street, lined with 150m2 plots on both sides, each plot surrounded by 1m high live hedge; Each plot has a 75m2 single story house with two bedrooms, a toilet, a kitchen and a living/ dining area. 27 Plan of two housing options studied Option A (Left) & Option B (right)

28 Houses are laid on a staggered form, with alternating houses having the legal minimum rear space (2.5m). Every other house has a larger rear space (and thus smaller front yard). For reasons of simplicity of the computer model, the internal partitions of the house are ignored; The house is constructed of 225mm thick brick walls, plastered both sides (outside rough plastered and dark coloured, inside lime plastered and white coloured); calicut tile roof on timber frame with flat asbestos sheet ceiling; 6mm thick, single glazed windows on wood frames; tiled floor on 100mm mass concrete; 28 Plan of two housing options studied Option A (Left) & Option B (right)

29 All windows are shaded by 1m wide horizontal shading devices; The house is considered air conditioned for the purpose of calculating the cooling load. The rate of infiltration is assumed to be 1 Air Change per Hour (ACH). In reality however, houses will not be air conditioned. This exercise was used solely for the calculation of potential energy savings. Internal temperature of the house is set lower at night and slightly higher during the day. The house is assumed to have four occupants. 29 Plan of two housing options studied Option A (Left) & Option B (right)

30 Simulation options: i. Main entrance facing East; ii.cement / fibre roof; iii.tile roof with Styrofoam insulation; iv.white painted roof cover Isometric view of thebasecase Option A (Left) & Option B (right)

31 Street Surface Tem perature Parametric modeling of building indoor climate shows that: Preferred orientation: Main entrance facing South Differences in energy saving between different housing options isminimal Preferred roof cover: Tile Roof insulation will reduce % of the cooling load Roof strategy: at least 20mm roof insulation White roof will reduce an additional 8% of the cooling load. Surface Tem mp. (oc) Surface Tem mp. (oc) NE-SW Street N-S Street NW-SE Street Staggered Bldg (NE-SW) Staggered Bldg (N-S) Green case Non-Asphalt Street :00 3:00 5:00 7:00 9:00 11:00 13:00 15:00 17:00 19:00 21:00 23:00 Backyard Surface Tem perature NE-SW Street N-S Street NW-SE Street Staggered Bldg (NE-SW) Staggered Bldg (N-S) Green case Non-Asphalt Street :00 3:00 5:00 7:00 9:00 11:00 13:00 15:00 17:00 19:00 21:00 23:00 Surface temperatures on the street-side (above) and rear-side (below) of dwellings

32 The best indoor comfort option is to paint theroof whiteand use roof insulation. The second best option would be to use roof insulation. Up to 3 deg. C reduction in indoor air temperature is possible with white roof/roof insulation combination. Nearly 2 deg. C reduction could be achieved by insulating the roof. (Such reductions are significant, considering the fairly constant and warm outdoor conditions prevailing in Sri Lanka s dry zone) In terms of layout, East West orientation (i.e. main entrance facing east) is seen as the worst option. o Indoor conditions in House Option B air temperature (above) operative temperature (below)

33 Rahula Attalage Energy efficient (green/ecological) & residential housing: Narein Perera presentation of innovative Chartered Architect t / Senior Lecturer nareinperera@gmail.com projects and case studies Deputy Vice Chancellor / Senior Professor University of Moratuwa Sri Lanka ASiL Sri Lankan Perspective 2 nd February 2015