Embodied carbon savings of co-living and implications for metrics

Tove Malmqvist; Johanna Brismark

doi:10.5334/bc.347

Figures & Tables

Table 1

Key facts about the three case studies (CS).

	CS1: TESTBED ASSESSMENT (Figures 1 and 2)		CS1: BUILDING-LEVEL ASSESSMENT (Figure 3)				CS2: BUILDING-LEVEL ASSESSMENT (Figure 4)
AS-BUILT DESIGN WITH FOUR STUDIOS	AS-BUILT DESIGN WITH ONE CO-LIVING UNIT	AS BUILT DESIGN	CO-LIVING DESIGN A	CO-LIVING DESIGN B	CO-LIVING DESIGN C	APARTMENT DESIGN	CO-LIVING DESIGN
Gross floor area (m²)	114	114	11,595	11,595	11,595	11,595	3,844	3,855
Residential floor area (RFA) (m²)	86	104	410 per typical floor plan; 6,609 in total	459 per typical floor plan; 8,153 in total	437 per typical floor plan; 8,104 in total	410 per typical floor plan; 8,046 in total	2,407	2,597
Main structural material and structural solution	n.a.		External load-bearing sandwich walls Prefabricated inner walls in concrete Prefabricated hollow-core concrete slabs In-situ cast concrete foundation				External stud wall in steel and primarily brick facade In-situ cast load-bearing inner walls and slabs in concrete In-situ cast concrete foundation
Number of floors	One		Three buildings: six to seven floors each with one floor underground				Seven (one floor underground)
System boundary for the building inventory	All building components that were subject to changes due to the co-living design in the interior of the testbed, i.e. interior walls and wall coverings, floor coverings, interior roof materials, doors, fixed furnishing and appliances including, e.g., whitegoods and sanitary goods. Other technical installations are excluded		All building components covered in the testbed assessment plus the rest of the building elements and components. The only components not covered include potential materials for soil stabilisation and groundwork preparations. This system boundary corresponds to the proposed system boundary for limit values in the climate declaration regulation in Sweden (Boverket 2023) If some building components, such as furnishing for kitchens and bathrooms, were missing in the model quantifications, these were manually added based on layout plans and typical kitchen and bathroom compositions Technical installations were included based on the standard value on embodied carbon for multifamily dwellings of 17.3 kg CO₂e/m² heated area from Malmqvist et al. (2021)

Original apartment layout (CS1) **(a)** and layout with a co-living unit (CS1) **(b)**.
*Source:* Figures and co-living design by Theory Into Practice (TIP), https://www.theoryintopractice.se/. Reproduced with permission.

CS1: One of the three buildings of Forskningen, including the KTH’s Live-in-Lab (LiL) testbed.
*Source:* Theory Into Practice (TIP). Reproduced with permission.

Layout plans of the studied co-living designs applied to the case study building Forskningen in CS1.
*Source:* Figures and co-living design by Theory Into Practice (TIP). Reproduced with permission.

Typical floor plans with original apartment layout (CS2) **(a)** and layout with co-living units (CS2) **(b)**.
*Note:* B = bathroom, K = kitchen, S = staircase.
*Source:* Figures and co-living design by Theory Into Practice (TIP). Reproduced with permission.

Embodied carbon (modules A1–A3) of the original apartment layout compared with the co-living layout of the KTH’s Live-in-Lab (LiL) in CS1.

Table 2

Overview of the fittings, furnishing and appliances included in embodied carbon assessments of bathrooms and kitchens of the case studies (CS), and the resulting embodied carbon.

	ROOM AND LAYOUT TYPE	SPECIFICATION OF INVENTORY	EMBODIED CARBON FOR MODULES A1–A3 (kg CO₂e)
CS1	Kitchen fittings, furnishing and appliances for one kitchen—co-living layout	Cabinet fittings, two sinks with water taps, and appliances in the form of two large fridge/freezers, two ovens, one stove with two hobs, one stove with four hobs, two fans, one dishwasher. Adapted for four to six students	1,450
	Kitchen fittings, furnishing and appliances for one kitchen—apartment layout	Cabinet fittings, one sink with water tap, and appliances in the form of one small fridge, one oven, one stove with two hobs, one fan	480
	Bathroom fittings furnishing and appliances for one bathroom—both co-living and apartment layout	Toilet, sink with water tap, bathroom cabinet, mirror, shower faucet with shower set and glass shower wall	220
CS2	Kitchen fittings, furnishing and appliances for one kitchen—large apartment of the original apartment layout	Cabinet fittings, one double sink with water taps, laminate countertop, and appliances in the form of two large fridge/freezers, one combined oven/stove with four hobs, one fan, one dishwasher	1,090
	Kitchen fittings, furnishing and appliances for one kitchen—small apartment of the original apartment layout	Cabinet fittings, one sink with water taps, laminate countertop, and appliances in the form of one large fridge/freezer, one combined oven/stove with four hobs, one fan, one small dishwasher	730
	Kitchen fittings, furnishing and appliances for one co-living unit—co-living layout	A bigger one plus a kitchenette with similar appliances as the apartment kitchen	2,230
	Bathroom fittings, furnishing and appliances for one bathroom—large apartment of the original apartment layout	Toilet, sink with water tap, two bathroom cabinets, shower faucet with shower set and glass shower wall, one laundry machine, one dryer	480
	Bathroom fittings, furnishing and appliances for one bathroom—small apartment of the original apartment layout	Toilet, sink with water tap, two bathroom cabinets, shower faucet with shower set and glass shower wall, one combined laundry machine/dryer	350
	Bathroom fittings, furnishing and appliances for one co-living unit—co-living layout	Toilet, sink with water tap, two bathroom cabinets, shower faucet with shower set and glass shower wall	230
Both CS	Apartment door	Steel	260
	Bathroom door	Wood	16
	Bedroom door	Wood (higher quality/classified for acoustics and fire)	57

Table 3

Embodied carbon (per floor area or running metre) for the internal fittings, furnishing and surface materials for different types of rooms, developed in CS2.

ROOM TYPE	SPECIFICATION OF INVENTORY	FLOOR AREA OR LINEAR MEASURE	EMBODIED CARBON FOR MODULE A1–A3 (kg CO₂e/m² FLOOR AREA OR RUNNING METRE
Ordinary apartment room, e.g. bedroom	Parquet floor, gypsum boards on walls, painted walls. No fittings and furnishing	13 m²	19
Bathroom 1	Completely tiled floor and walls, plywood and wet room gypsum boards, fittings according to small apartment in Table 2	4.2 m²	190
Bathroom 2	Completely tiled floor and walls, plywood and wet room gypsum boards, fittings according to large apartment in Table 2	5 m²	200
Bathroom 3	Tiled floor, painted walls, plywood and wet room gypsum boards, toilet, sink with water tap, bathroom cabinet, mirror	2 m²	140
Bathroom 4	Completely tiled floor and walls, plywood and wet room gypsum boards, fittings according to co-living unit in Table 2	3.9 m²	170
Bathroom 4, timber slabs	Completely tiled floor and walls, plywood and wet room gypsum boards, fittings according to co-living unit in Table 2, additional floor work due to timber slab	3.9 m²	180
Large apartment kitchen	PVC floor under and tiling above countertop, and kitchen fittings and furnishing according to large apartment in Table 2	5.2 m	220
Small apartment kitchen	PVC floor under and tiling above countertop, and kitchen fittings and furnishing according to small apartment in Table 2	3.1 m	240
Co-living kitchen	PVC floor under and tiling above countertop, and kitchen fittings and furnishing according to co-living unit in Table 2	13 m	180

[i] Note: PVC = polyvinyl chloride.

Embodied carbon of the entire buildings (modules A1–A3) with a co-living-respective apartment design, using two different reference units.

Embodied carbon of the entire buildings (modules A1–A3) with a co-living-respective apartment design, presented per designed number of residents.

Table 4

Floor areas and numbers of residents in the two case studies.

CASE STUDY	DESIGN ALTERNATIVE	AVERAGE RESIDENTIAL FLOOR AREA PER PERSON IN TYPICAL FLOOR PLAN (m²)	RESIDENTS PER TYPICAL FLOOR PLAN (n)	ACCESSIBLE FLOOR AREA PER PERSON IN A TYPICAL FLOOR PLAN (m²)
CS1	Co-living A	19.0	24	55
	Co-living B	22.5	24	57
	Co-living C	20.5	20	55
	Forskningen (apartment design)	21.5	19	22
		AVERAGE RESIDENTIAL FLOOR AREA PER PERSON (m²)	RESIDENTS IN THE BUILDING (n)	ACCESSIBLE FLOOR AREA PER PERSON (m²)
CS2	Co-living	32	81	109
CS2	Original apartment design	34	70	34

Conceptual illustration of the eco-efficiency of different home designs applied to the case studies in the study.

Table 5

Embodied carbon savings when one co-living unit for seven elderly women in CS2 is constructed instead of the new construction of buildings that it is assumed that the co-living unit can replace.

	NEW CONSTRUCTION	RESIDENTIAL FLOOR AREA (m²)	EMBODIED CARBON (kg CO₂e)
Base scenario	New construction of two single-family buildings	218	37,900
	New construction of five apartments in multifamily buildings	350	152,500
	Sum	568	190,400
Co-living scenario	New production of a co-living unit with seven bedrooms	222	96,700
Co-living scenario	Sum	222	96,700

Embodied carbon savings of co-living and implications for metrics

Figures & Tables

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Figure 1

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Figure 5

Table 2

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Table 4

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Table 5

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