Source
doi:10.1061/JUPDDM.UPENG-5334 — original publication (opens in a new tab; the file is not redistributed)
Summary
Compiled research note on Gullberg, Wang & Eriksson (2025), Journal of Urban Planning and Development (ASCE). The primary paper is the first peer-reviewed study to co-calculate self-sufficiency across energy, water, and nutrients within a single consistent system boundary for an urban neighbourhood. Uses eco-cycle modelling with a transdisciplinary co-design process (4 workshops, 49 participants) in Knivsta Municipality, Sweden. Three neighbourhood density cases tested. Results represent maximum technical annual potentials; temporal/seasonal variation excluded. Open access (CC BY 4.0).
Why this matters for NI: Provides the canonical multi-domain SSI formula, a seven-domain metabolic function framework, and empirical benchmarks for electricity/water/heat/food/nutrient self-sufficiency at neighbourhood scale. Primary source now ingested as LIT_022 — cite LIT_022 in preference to CR_006 for all quantitative claims. CR_006
Key claims
SSI formula and seven-domain framework
- SSI_i = (local provisioning potential for function i / total annual demand for function i) × 100% — the canonical multi-domain formula, applied consistently across all seven metabolic functions within a single boundary. CR_006
- Seven vital metabolic functions for neighbourhood-scale self-sufficiency: (1) electricity supply, (2) heat supply, (3) transportation (biogas vehicle fuel), (4) freshwater supply, (5) graywater management, (6) food supply (vegetable consumption), (7) nutrient recovery (nitrogen and phosphorus). CR_006
- Local provisioning potential for each function is constrained by the binding limiting factor specific to each solution: available roof area (PV, rainwater), green area (urban farming, graywater treatment), volume of wastewater (biogas, nutrient recovery), or surplus heat sources. CR_006
Electricity
- Electricity: 140%–260% self-sufficiency achieved in all three density cases from roof-mounted PV alone — even at 59.5°N (Swedish latitude with ~1,800 h sunshine/year); east–west roof configuration achieves 63%–111% depending on case. CR_006
- Roof-mounted south-facing PV alone achieves 40%–70% of electricity demand depending on density; east–west mounting adds significant additional yield due to morning and afternoon generation profile. CR_006
Heat
- Heat is the most constrained domain in dense urban contexts: combining all available local sources (graywater heat recovery via heat pump 40%, commercial surplus heat 15%, biogas from blackwater 6%, biogas from food waste 5%), dense multifamily Case 1 achieves only 66% heat self-sufficiency. Single-family cases achieve 31–48%. CR_006
- Imported biofuel for biomass boilers could supplement heat SSI but is excluded from “local provisioning” — a boundary decision that would increase the figure if relaxed for a rural community with local forestry access. CR_006
Freshwater and graywater
- Freshwater: 100% (Case 1, dense), 140% (Case 2), 220% (Case 3) — rainwater harvesting from roof area meets or exceeds demand at Swedish rainfall levels (~600 mm/yr). CR_006
- Graywater management green area capacity vastly exceeds treatment demand: only ~3% of Case 1’s green area needed for nature-based graywater infiltration — graywater management is not a binding constraint in any neighbourhood configuration tested. CR_006
Food (vegetables)
- Vegetable supply SSI is the most density-sensitive domain: dense multifamily (72 m²/person green area) achieves 38%; single-family cases achieve 210%–400%. Note: vegetables are only part of total food consumption — even 400% vegetable SSI does not imply full food self-sufficiency. CR_006
Nutrient recovery
- Nitrogen recovery: 78% in all cases (consistent across density); phosphorus recovery: 98% in all cases — nutrient recovery from blackwater anaerobic digestion is primarily volume-dependent (per-capita), not density-dependent. CR_006
Key design finding
- Building density and green area share are the dominant variables across all SSI domains simultaneously — the single most influential design decision for multi-domain self-sufficiency is how much green/unbuilt area is preserved relative to population. CR_006
Transferability
- The SSI formula, seven-domain framework, and input data categories (roof area, green area, climate, per-capita consumption) apply within the stated boundary conditions; all seven input data types have equivalents in NZ data sources (NIWA, Stats NZ, BRANZ HEEP, MfE biosolids guidelines). NZ-specific calibration targets: electricity demand baseline (RT_077); per-capita water consumption (RT_078). Annual calculations only — seasonal variation requires supplementary analysis for battery sizing and off-grid design. LIT_022
Research targets
Documents to retrieve
- [RT_069] Gullberg Y, Wang Z & Eriksson O (2026) — companion LCA paper: “Exploring circular and self-sufficient resource management of energy, water, and wastewater systems in an urban neighbourhood: A life-cycle assessment” — Sustainable Production and Consumption, doi:10.1016/j.spc.2025.01.017 — quantifies environmental impact of the same Knivsta system; directly complementary to CR_006 SSI results
Connections
Links to
Sources (1): LIT_022