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Landscaping design

LANDSCAPING DESIGN process of Villa Groveland included numerous efforts to improve environmentally sound green practices and water efficiency features. In the course of construction numerous precautions were made to minimize long-term damage to the building lot and make sure that most of the indigenous plants will be contained in undisturbed areas.

EROSION AND SEDIMENTATION CONTROL measures were taken to stockpile and protect disturbed soil using ~ 500 lin. ft of retaining walls, on-site rain garden, erosion control pond and slope blankets were used to keep soil stabilized. Mulch covering was placed around plants to reduce erosion and water loss. Extensive use of mulch helps to regulate soil temperature, at the same time upon decomposition organic mulches serve as soil amendments.

CONVENTIONAL TURF AREA was limited to about 15.27% of the total softscaped areas (see conventional turf area information for more details). About 67% of the buildable lot can be attributed to water-permeable area. High-albedo concrete was installed with solar reflectance index (SRI) of at least 29 was used for more than 50% of sidewalks, patio, courtyard and parking lot) to eliminate heat islands and ensure proper temperature balance in hot summer season.

SELECTION OF PLANTS, shrubs and tree species was made with special care to exclude any invasive plants anywhere near the property. Special preference was given to native and drought-tolerant plants and turf. Draught-tolerant plant species amount to 28 out of total 44 presently installed or expected to be planted on the lot in the near future. To ensure efficient pest control the mature plants are installed at least 2 feet from the house. For a detailed list of trees, shrubs and plants check here.

                                                                                      
                                                    LANDSCAPED AREAS SUMMARY*

                                             *For more details see Landscaping and Grading Plan

REDUCTION OF IRRIGATION DEMAND contributed greatly to water conservation system of the landscape area. Nearly 50% reduction in average irrigation demand was achieved.

Climatic Data for Vancouver Area Major Soil Landscape Regions: Annual Means 
(source: BC Ministry of Environment)

Calculations

Step 1. Baseline irrigation water usage calculation

Baseline usage = Landscaped Area * ET₀ * 0.62

    Landscape area: 16,978 sft

    Sodded lawn area: 2,592 sft (15.27%)

Baseline usage =  16,978 * 1.34 * 0.62 = ~ 14,105

Step 2. Design case irrigation water usage calculation

Design case usage = (LA * ET_L  / IE) * CF * 0.62, where

ET₀ = 1.34

                        K_L = K_S * K_MC = 0.575

K_S (species factor)               = 0.575 (trees & shrubs with limited turf)

K_MS (microclimate factor)      = 1 i.e. (0.8 + 1 +1 +1.2)/4

average shading (0.8)

low sun exposure (1.0)

high protection from wind (1.0)

average windy area (1.2)

ET_L = ET₀ * K_L = 1.34 * 0.575 = 0.7705

IE (irrigation efficiency)

           spray rotors with rain sensor (front)    = 0.8;

           point source/drip (backyard)                 = 0.9;          average IE = 0.85

CF (control factor) = 0.75

(weather-based irrigation control manager e.g. RainBird), min. water savings 25%

Thus for our design case usage (16,978 *0.7705/0.85)*0.75*0.62 = ~7,156
 

Step 3. Percentage reduction in irrigation water demand

Percentage reduction:  14,105 – 100%, 7,156 – 50.73%, i.e. 49.27%