Non-Functional Requirements (NFRs) Framework for Software Systems

Overview

Sustainability and Resource Efficiency Non-Functional Requirements (NFRs) define how efficiently a software system should consume compute, storage, memory, network, energy, and related infrastructure resources while reducing unnecessary waste and supporting sustainable operations.

These requirements complement cost, performance, scalability, and platform NFRs. Resource-efficient systems can reduce operating cost, improve performance, lower environmental impact, improve capacity utilization, and avoid avoidable infrastructure expansion.

Best Practice: Define compute efficiency non-functional requirements

Description

Compute efficiency NFRs define how much CPU, memory, runtime, job execution, concurrency, or model inference capacity a system should consume relative to workload. They should address unnecessary processing, inefficient algorithms, idle resources, and oversized infrastructure.

Benefits

Compute efficiency requirements reduce operating cost, improve performance, increase platform capacity, and reduce energy consumption associated with avoidable processing.

Example non-functional requirements

• Batch processing jobs shall complete within the approved processing window using no more than the approved compute class and concurrency limits for the baseline workload.

• Validation method: Validate through batch performance test, resource utilization monitoring, workload review, and capacity report comparison.

• Example validation evidence: Performance test report, CPU/memory dashboard, job runtime report, workload profile, and capacity approval.

• Background jobs shall not continue consuming production compute resources when no eligible work is available.

• Validation method: Validate through idle-state monitoring, scheduler inspection, resource usage testing, and production telemetry review.

• Example validation evidence: Scheduler configuration, idle resource dashboard, test results, telemetry export, and defect closure record.

Related stakeholders

Typical stakeholders include architects, developers, platform teams, SRE teams, FinOps teams, sustainability stakeholders, and operations teams.

Related lifecycle phases

Compute efficiency NFRs are defined during architecture and design; implemented during application and platform engineering; validated during performance and capacity testing; and monitored in production through resource utilization dashboards.

Best Practice: Define storage efficiency non-functional requirements

Description

Storage efficiency NFRs define how data, logs, files, backups, indexes, snapshots, analytics datasets, and artifacts should be stored, compressed, tiered, deduplicated, archived, and purged. They must align with retention, legal hold, recoverability, privacy, and audit requirements.

Benefits

Storage efficiency requirements reduce waste, improve retrieval and backup performance, lower storage cost, and support sustainable data lifecycle management.

Example non-functional requirements

• The system shall archive or purge non-record operational logs according to approved retention rules so that production log storage does not grow without defined lifecycle control.

• Validation method: Validate through retention configuration review, log volume trend analysis, purge test execution, and records/privacy approval.

• Example validation evidence: Retention mapping, log storage trend report, purge test evidence, approval record, and exception list.

• Large generated reports and exports shall be retained only for the approved retention period unless legal hold or records obligations require longer retention.

• Validation method: Validate through storage lifecycle policy review, sample artifact inspection, legal hold check, and purge evidence review.

• Example validation evidence: Lifecycle policy configuration, artifact inventory, legal hold status, purge logs, and records management approval.

Related stakeholders

Typical stakeholders include data owners, platform teams, database administrators, records managers, privacy teams, FinOps teams, and application owners.

Related lifecycle phases

Storage efficiency NFRs are defined during data, retention, and platform design; implemented through lifecycle policies and storage architecture; validated during system testing and production readiness; and monitored through capacity and cost reviews.

Best Practice: Define network efficiency non-functional requirements

Description

Network efficiency NFRs define how systems should reduce unnecessary data movement, optimize payload size, control egress, cache appropriately, compress data, batch transfers, and avoid wasteful cross-region or cross-cloud traffic.

Benefits

Network efficiency improves performance, reduces latency, lowers egress cost, reduces platform load, and supports more sustainable system operation.

Example non-functional requirements

• The system shall avoid unnecessary cross-region data transfer for routine processing unless required by approved availability, compliance, or Disaster Recovery (DR) design.

• Validation method: Validate through architecture review, network flow analysis, cloud egress report review, and production telemetry inspection.

• Example validation evidence: Architecture decision record, network flow diagram, egress cost report, telemetry samples, and approval record.

• API responses for high-volume endpoints shall use approved pagination, filtering, compression, or caching patterns to avoid excessive payload transfer.

• Validation method: Validate through API performance testing, payload inspection, client behavior review, and production traffic monitoring.

• Example validation evidence: API test report, sample payloads, caching configuration, traffic dashboard, and defect closure evidence.

Related stakeholders

Typical stakeholders include application architects, integration architects, platform teams, network teams, FinOps teams, SRE teams, and performance engineers.

Related lifecycle phases

Network efficiency NFRs are defined during architecture and API design; implemented during service and network configuration; validated during performance and integration testing; and monitored through traffic, latency, and egress dashboards.

Best Practice: Define energy and carbon-aware operating non-functional requirements

Description

Energy and carbon-aware operating NFRs define how workloads may consider energy usage, carbon intensity, region selection, workload scheduling, autoscaling, right-sizing, and idle resource elimination where such practices are feasible and aligned with business, compliance, and availability needs.

Benefits

Carbon-aware and energy-aware requirements support sustainability goals while encouraging efficient design, responsible capacity planning, and removal of unnecessary infrastructure consumption.

Example non-functional requirements

• Non-critical batch analytics workloads shall be scheduled during approved low-impact windows where doing so does not violate business, data freshness, security, or compliance requirements.

• Validation method: Validate through scheduler review, workload freshness validation, business approval, and production execution monitoring.

• Example validation evidence: Scheduler configuration, data freshness report, business approval, workload execution history, and exception record.

• The platform shall review rightsizing recommendations for persistent compute resources at least quarterly and document accepted, deferred, or rejected actions.

• Validation method: Validate through rightsizing report review, action tracking, resource utilization analysis, and governance approval.

• Example validation evidence: Rightsizing report, action log, utilization dashboard, approval record, and exception rationale.

Related stakeholders

Typical stakeholders include sustainability stakeholders, FinOps teams, platform teams, application owners, architects, operations teams, and business owners.

Related lifecycle phases

Energy and carbon-aware NFRs are defined during architecture and operating model design; validated during workload scheduling and rightsizing reviews; and monitored through resource, cost, and sustainability reporting.

Best Practice: Define waste reduction and lifecycle efficiency non-functional requirements

Description

Waste reduction and lifecycle efficiency NFRs define how teams identify and remove unused environments, idle resources, stale data, obsolete artifacts, duplicate processing, unused licenses, and retired integrations or systems.

Benefits

Waste reduction improves cost, security, sustainability, and operational simplicity. It also reduces attack surface and technical clutter.

Example non-functional requirements

• Non-production environments shall have approved lifecycle rules for creation, ownership, expiration, shutdown, and deletion.

• Validation method: Validate through environment inventory review, ownership review, expiration policy inspection, and cleanup execution evidence.

• Example validation evidence: Environment inventory, ownership list, lifecycle policy, cleanup logs, and platform approval.

• Unused storage buckets, databases, queues, topics, secrets, and service accounts shall be identified and reviewed for retirement at least quarterly.

• Validation method: Validate through platform inventory scan, owner attestation, retirement review, and security validation.

• Example validation evidence: Inventory scan, owner attestation records, retirement backlog, security review, and deletion evidence.

Related stakeholders

Typical stakeholders include platform teams, application teams, security teams, FinOps teams, operations teams, sustainability stakeholders, and portfolio managers.

Related lifecycle phases

Waste reduction NFRs are defined during platform governance and operating model design; implemented through inventory, tagging, and automation; validated during periodic reviews; and improved through lifecycle and portfolio governance.

Best Practice: Define sustainability and resource efficiency validation and evidence non-functional requirements

Description

Sustainability and resource efficiency validation NFRs define the evidence required to prove that resource usage, waste reduction, storage lifecycle, rightsizing, network efficiency, and operating efficiency expectations have been assessed and managed.

Benefits

Validation evidence turns sustainability from aspiration into measurable operating discipline and supports governance, FinOps, and platform improvement decisions.

Example non-functional requirements

• Each production workload shall retain evidence of resource utilization review before major capacity expansion or architecture scaling decisions.

• Validation method: Validate through capacity review, utilization dashboard inspection, cost/resource trend review, and approval checkpoint.

• Example validation evidence: Utilization report, capacity forecast, scaling decision record, cost/resource trend, and approval evidence.

• Resource efficiency improvement actions shall include baseline measurement, target outcome, implementation record, and post-change validation.

• Validation method: Validate through before/after measurement review, change record inspection, and stakeholder approval.

• Example validation evidence: Baseline dashboard, change record, post-change dashboard, savings or efficiency report, and approval record.

Related stakeholders

Typical stakeholders include sustainability teams, FinOps teams, platform teams, architects, product owners, operations teams, and governance stakeholders.

Related lifecycle phases

Sustainability validation NFRs are defined during governance and architecture planning; validated during release readiness, operational review, and optimization cycles; and monitored continuously through dashboards and periodic reporting.