16-0428 v3.0/Private Residence at West 42nd/Proposed Methodology for Accommodating Expansion of the Single Family Residence Requirement

QUESTION:

The following narrative has been prepared in response to the Living Building Challenge dialogue post (ID:3511) and its response dated 01/26/2016. We can confirm that the project in question accommodates three generations, or family units (as derived from the previous response). This consists of parents (1), adult child and niece (2) and grandparents (3). The design team have carried out a detailed review of the project areas, and subdivided these areas based on use type (sleeping spaces, living spaces, circulation spaces). It was noted as part of this exercise that of the total gross building area, external wall construction area comprises 17%. Given that the intent of Imperative 15 is focused on creating human-scaled places that promote interaction, we do not feel that the inclusion of wall assembly width best represents the objective when considering single family residence size (i.e. liveable space). For this project, the design team have adopted PassiveHouse (Passivhaus) standard approaches to minimising heating demand through investing in an extremely efficient building envelope. This approach results in deeper external wall, floor and roof assemblies that accommodate added insulation to achieve the required efficiency values. By requiring gross building area as the metric to establish compliance for this requirement, we feel this unfairly penalises approaches that employ ‘fabric first’ principles to reduce energy demand and ultimately achieve net zero energy. The City of Vancouver have recently provided relaxation on their existing building permit calculation methodology to discount additional wall assembly thickness from gross building floor area calculations, where an increased envelope efficiency is sought. We request that the metric to establish compliance with this requirement is revised to net floor area, in light of the above and to better reflect the intent of this Imperative (and focus on ‘liveable area’). In order to justify a proposed increase in single family residence size above that prescribed (425m²), the design team assessed the spatial proportions of living area vs sleeping area and circulation zones that accommodate the current 3 family units. Living Areas contribute 42% of total, whereas sleeping areas contribute 26% and circulation 32% of total net floor area. If one bedroom was removed (to now accommodate 2 family units) and living area reduced to maintain the same proportion to sleeping area, we find that total floor area (including wall assembly width) is now compliant with the 425m² requirement. As such, the increase in floor area above the 425m² requirement is provided to accommodate the 3rd generation within the same area proportions. The above assessment justifies that an increase in family units beyond that considered to be typical for a single family residence has been accommodated along with an appropriate increase in sleeping and living area that aligns with the intent of this Imperative. As previously expressed, the client for this project is Chinese, and a key cultural difference with Asian families is that family homes often span three or more generations all living together. In this case, there are three different generations within one home. As shown above, the increase in living area has been carefully considered to cater for this increase in occupants (above a typical western single family home composition) without compromising the true intent of the requirement – living within ones means.

ANSWER:

It is acceptable to expand the maximum size for a single family residence when it accommodates three or more family units or generations since such arrangements promote multi-generational / multi-family interaction, in keeping with the intent of this Imperative. The maximum single family residence size limit of 425 square meters can be exceeded through use of the following new Exception:   

I15-E4 Multi-generational or Multi-family Residences 
Single family residences which are home to three or more generations or family units (i.e. parents and dependent children or independent adults) may have a building area that is up to 100 square meters (~1000 square feet) greater than the 425 square meter limit.    

Documentation:
I15-a Exception Narrative - A narrative identifying the three or more generations or family units who will be occupying the project, and describe how the design has attempted to minimize the additional area needed.


Post ID 5451

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