Scope: What is in Scope of the Sustainability Pillar?

What is in scope of this pillar?

The Sustainability pillar of WAF++ addresses all aspects of cloud IT operations that have a directly measurable impact on energy consumption and greenhouse gas emissions.

In Scope

Area	Description	Relevant Controls
Cloud Compute Emissions	EC2, Lambda, containers, Kubernetes workloads — energy consumption from CPU, RAM, GPU	WAF-SUS-010, WAF-SUS-020, WAF-SUS-040
Software Energy Efficiency	Algorithms, architecture patterns, database queries, event-driven vs. polling	WAF-SUS-070
Cloud Storage Emissions	S3, EBS, Azure Blob, GCS — energy proportional to stored data volume	WAF-SUS-050
Network & Data Transfer	Cross-region transfer, CDN, compression, VPC endpoints	WAF-SUS-080
ESG Reporting & CSRD Compliance	Data collection, GHG Protocol Scope 3 attribution, ESRS E1 reporting	WAF-SUS-090, WAF-SUS-010
Region & Placement Decisions	Carbon intensity of selected cloud regions	WAF-SUS-030
Workload Scheduling	Temporal shifting of batch jobs to low-emission windows	WAF-SUS-060
Sustainability Governance	Debt register, quarterly reviews, goal tracking	WAF-SUS-100

Area

Description

Relevant Controls

Cloud Compute Emissions

EC2, Lambda, containers, Kubernetes workloads — energy consumption from CPU, RAM, GPU

WAF-SUS-010, WAF-SUS-020, WAF-SUS-040

Software Energy Efficiency

Algorithms, architecture patterns, database queries, event-driven vs. polling

WAF-SUS-070

Cloud Storage Emissions

S3, EBS, Azure Blob, GCS — energy proportional to stored data volume

WAF-SUS-050

Network & Data Transfer

Cross-region transfer, CDN, compression, VPC endpoints

WAF-SUS-080

ESG Reporting & CSRD Compliance

Data collection, GHG Protocol Scope 3 attribution, ESRS E1 reporting

WAF-SUS-090, WAF-SUS-010

Region & Placement Decisions

Carbon intensity of selected cloud regions

WAF-SUS-030

Workload Scheduling

Temporal shifting of batch jobs to low-emission windows

WAF-SUS-060

Sustainability Governance

Debt register, quarterly reviews, goal tracking

WAF-SUS-100

Outside of Scope

Area	Justification
Office building emissions	Building energy, heating, air conditioning → facility management, not IT architecture
Employee travel	Business travel, commuting → HR/travel policy, unless IT-driven (remote-first decisions)
On-premise hardware procurement	Embodied carbon of self-managed hardware → only in scope for hybrid scenarios with IaC management
Product use by customers	CO₂ impact of own software on end-user devices → Scope 3 Category 11 of own customers (upstream)
Software vendor supply chain	CO₂ footprint of SaaS suppliers → outside the directly controllable area

Area

Justification

Office building emissions

Building energy, heating, air conditioning → facility management, not IT architecture

Employee travel

Business travel, commuting → HR/travel policy, unless IT-driven (remote-first decisions)

On-premise hardware procurement

Embodied carbon of self-managed hardware → only in scope for hybrid scenarios with IaC management

Product use by customers

CO₂ impact of own software on end-user devices → Scope 3 Category 11 of own customers (upstream)

Software vendor supply chain

CO₂ footprint of SaaS suppliers → outside the directly controllable area

Hybrid scenarios (on-premise + cloud) extend the scope: when on-premise infrastructure is managed via IaC, WAF-SUS controls apply accordingly to the IaC-governed parts.

Brownfield vs. Greenfield

Greenfield: New Workloads and Services

For new developments, sustainability can be built in from the start:

ARM/Graviton instances from day one (no migration effort)
Green regions as the default deployment target
Lifecycle policies as part of the IaC template
SCI as a quality attribute in the architecture review
Batch scheduling set to off-peak

Recommendation: For greenfield workloads, all WAF-SUS controls are immediately applicable. There is no technical justification for x86 as default or infinite retention in new developments.

Brownfield: Existing Systems and Legacy Infrastructure

For existing systems, prioritization by impact/effort is advisable:

Priority	Measure	Justification	Control
1 – Immediate	Lifecycle policies on S3/CloudWatch	Minimal effort, immediate impact, no compatibility risks	WAF-SUS-050
1 – Immediate	Non-prod scheduled shutdown	No code changes needed; typically 60–70% savings during non-business hours	WAF-SUS-040
2 – Medium-term	Migrate Lambda to arm64	Usually no code changes for Python/Node/Java; 20% efficiency gain	WAF-SUS-020
2 – Medium-term	Activate CDN and compression	Configuration change, no application change	WAF-SUS-080
3 – Project-based	Migrate EC2 instances to Graviton	Compatibility test required; x86-only binaries are blockers	WAF-SUS-020
4 – Strategic	Region migration to greener regions	Only for planned migrations or where compliance requirements allow	WAF-SUS-030

Priority

Measure

Justification

Control

1 – Immediate

Lifecycle policies on S3/CloudWatch

Minimal effort, immediate impact, no compatibility risks

WAF-SUS-050

1 – Immediate

Non-prod scheduled shutdown

No code changes needed; typically 60–70% savings during non-business hours

WAF-SUS-040

2 – Medium-term

Migrate Lambda to arm64

Usually no code changes for Python/Node/Java; 20% efficiency gain

WAF-SUS-020

2 – Medium-term

Activate CDN and compression

Configuration change, no application change

WAF-SUS-080

3 – Project-based

Migrate EC2 instances to Graviton

Compatibility test required; x86-only binaries are blockers

WAF-SUS-020

4 – Strategic

Region migration to greener regions

Only for planned migrations or where compliance requirements allow

WAF-SUS-030

Sustainability vs. Cost Optimization: Where they overlap

The Sustainability pillar and the Cost Optimization pillar are related, but not identical:

Aligned Goals (Win-Win)

Measure	Cost Impact	Sustainability Impact
Eliminate idle resources	Direct cost savings	Direct emission reduction
ARM/Graviton instead of x86	20–40% cheaper at equivalent performance	20–40% less energy per compute unit
Storage lifecycle tiering	Cheaper storage tiers	Less energy in hot storage tiers
CDN and compression	Reduced egress costs	Less network energy per request
Spot instances for batch	60–90% cost reduction	Better utilization of shared infrastructure

Measure

Cost Impact

Sustainability Impact

Eliminate idle resources

Direct cost savings

Direct emission reduction

ARM/Graviton instead of x86

20–40% cheaper at equivalent performance

20–40% less energy per compute unit

Storage lifecycle tiering

Cheaper storage tiers

Less energy in hot storage tiers

CDN and compression

Reduced egress costs

Less network energy per request

Spot instances for batch

60–90% cost reduction

Better utilization of shared infrastructure

Diverging Goals (Sustainability > Cost)

Scenario	Cost Perspective	Sustainability Perspective
Choosing green regions	Green regions (e.g. Stockholm) can be more expensive than us-east-1	Emission reduction from renewable energy outweighs the additional cost
Buying CO₂ offsets	Additional cost without performance benefit	Last resort for achieving net-zero targets
Building a CSRD reporting system	Significant investment in tooling and processes	Regulatory obligation; without this investment, fines are at risk
Implementing SCI measurement	Engineering effort without direct cost return	Prerequisite for emission reduction targets and ESG reporting

Scenario

Cost Perspective

Sustainability Perspective

Choosing green regions

Green regions (e.g. Stockholm) can be more expensive than us-east-1

Emission reduction from renewable energy outweighs the additional cost

Buying CO₂ offsets

Additional cost without performance benefit

Last resort for achieving net-zero targets

Building a CSRD reporting system

Significant investment in tooling and processes

Regulatory obligation; without this investment, fines are at risk

Implementing SCI measurement

Engineering effort without direct cost return

Prerequisite for emission reduction targets and ESG reporting

Cost optimization and sustainability are structurally aligned — but sustainability has further-reaching requirements (reporting, governance, CSRD compliance) that cost optimization does not cover. Both pillars should be optimized together in practice.

Regulatory Environment

Framework	Type	IT Relevance
EU CSRD	EU Regulation (Directive 2022/2464)	Mandatory for large companies from 2025; subsidiaries from 2026. Requires ESRS E1 (climate) including Scope 3.
ESRS E1	EU Sustainability Reporting Standard	Specifies disclosure requirements for climate change; Scope 1/2/3 emissions, reduction targets.
GHG Protocol	International standard	De facto standard for greenhouse gas inventory and reporting. Basis for CSRD implementation.
SBTi (Science Based Targets)	Voluntary commitment framework	Companies commit to science-based emission reduction targets (1.5°C pathway).
ISO 14001	Management standard	Environmental management system; relevant as a process framework for sustainability governance.
Green Software Foundation	Best practice organization	Software Carbon Intensity (SCI) standard; carbon aware computing patterns; practical guidelines.
EU Taxonomy Regulation	EU Regulation	Classifies economic activities as "sustainable" or not. Relevant for investor communications.

Framework

Type

IT Relevance

EU CSRD

EU Regulation (Directive 2022/2464)

Mandatory for large companies from 2025; subsidiaries from 2026. Requires ESRS E1 (climate) including Scope 3.

ESRS E1

EU Sustainability Reporting Standard

Specifies disclosure requirements for climate change; Scope 1/2/3 emissions, reduction targets.

GHG Protocol

International standard

De facto standard for greenhouse gas inventory and reporting. Basis for CSRD implementation.

SBTi (Science Based Targets)

Voluntary commitment framework

Companies commit to science-based emission reduction targets (1.5°C pathway).

ISO 14001

Management standard

Environmental management system; relevant as a process framework for sustainability governance.

Green Software Foundation

Best practice organization

Software Carbon Intensity (SCI) standard; carbon aware computing patterns; practical guidelines.

EU Taxonomy Regulation

EU Regulation

Classifies economic activities as "sustainable" or not. Relevant for investor communications.

For organizations subject to CSRD, sustainability reporting is not a best practice — it is a legal obligation with potential for sanctions. Architects and engineers should be aware of their organization’s CSRD obligations.