Myths vs. realities: Energy efficiency & demand response — what the evidence actually supports

Buildings account for approximately 40% of total energy consumption in the United Kingdom and 35% of its territorial carbon emissions, yet the average UK commercial building wastes 20 to 30% of the energy it consumes according to the Carbon Trust's 2025 Commercial Building Energy Survey. With energy prices remaining elevated following the 2022 to 2024 price shocks and the UK's legally binding target of net zero by 2050, energy efficiency and demand response have attracted enormous investment, bold vendor claims, and no small amount of confusion about what these strategies can realistically deliver.

Why It Matters

The UK government's Energy Efficiency Taskforce estimates that improving building energy efficiency could reduce national energy demand by 15% by 2035, equivalent to taking 10 million cars off the road (HM Government, 2025). Demand response, the practice of shifting or reducing electricity consumption during peak periods in exchange for financial incentives, has been identified by National Grid ESO as critical to managing a power system targeting 95% low-carbon electricity by 2030. The combined addressable market for energy efficiency services and demand response in the UK exceeds £12 billion annually (UK Energy Research Centre, 2025).

However, the gap between what is promised and what is delivered remains substantial. Building energy management system (BEMS) vendors routinely claim 30 to 40% energy savings, demand response aggregators project revenues that rarely materialise at the quoted levels, and retrofit programs frequently underperform their design specifications. Sustainability professionals responsible for building portfolios, corporate energy procurement, and net zero target delivery need a clear-eyed assessment of where the evidence is strong, where claims are overstated, and where the real value lies.

Key Concepts

Energy efficiency reduces the total amount of energy required to deliver a given service: lighting, heating, cooling, or industrial process output. It encompasses building fabric improvements (insulation, glazing, air tightness), equipment upgrades (LED lighting, high-efficiency boilers, heat pumps), and controls optimisation through building energy management systems.

Demand response (DR) shifts or curtails electricity consumption in response to grid signals, market prices, or direct instructions from grid operators. It does not necessarily reduce total energy consumption but changes when energy is used. DR can be implicit (consumers responding to time-of-use tariffs) or explicit (aggregators remotely adjusting loads under contract to the system operator).

The distinction matters because vendors sometimes conflate the two, claiming "demand response saves energy" when it primarily shifts load. True energy savings and demand flexibility are complementary strategies, but they operate through different mechanisms and deliver different value streams.

Myth 1: Smart Building Systems Deliver 30 to 40% Energy Savings Out of the Box

BEMS and IoT-based building automation vendors frequently headline savings of 30 to 40% in marketing materials. The evidence supports more modest outcomes. The Better Buildings Partnership's 2025 analysis of 340 UK commercial buildings that installed BEMS upgrades between 2021 and 2024 found median energy savings of 12 to 18%, with the range spanning 5 to 28% depending on building type, baseline condition, and the quality of ongoing commissioning (BBP, 2025). Buildings with poor baseline performance and no prior controls saw savings at the upper end, while well-managed buildings with existing BMS infrastructure often achieved 5 to 10%.

The gap between quoted and actual savings stems from several factors. Vendor projections typically assume optimal commissioning, consistent occupant behaviour, and ongoing maintenance of control set points. In practice, the UK's Chartered Institution of Building Services Engineers (CIBSE) has documented that 60% of BEMS installations experience "set point drift" within 18 months, where temperature schedules, ventilation rates, and lighting controls are manually overridden and never reset (CIBSE, 2024). Without dedicated building performance monitoring and regular recommissioning, savings degrade by 2 to 5% per year.

The reality: smart building systems deliver genuine savings, typically 12 to 18% in well-implemented projects with ongoing management. The 30 to 40% figures are achievable only in specific circumstances: poor-performing buildings with no existing controls that receive comprehensive retrofits and continuous commissioning.

Myth 2: Demand Response Is Free Revenue for Building Operators

Demand response aggregators market their services as risk-free revenue: allow remote control of your HVAC, lighting, or battery systems, and earn payments for providing flexibility to the grid. National Grid ESO's capacity market and balancing services do provide revenue streams, but the financial reality is more nuanced.

An analysis by the Association for Decentralised Energy covering 120 UK commercial demand response participants found that average annual revenues ranged from £8 to £25 per kilowatt of flexible capacity, with the median at £14/kW (ADE, 2025). For a typical 500 kW office building offering 100 kW of demand flexibility, this translates to £1,400 per year in revenue against setup costs of £15,000 to £30,000 for sub-metering, control integration, and aggregator platform connection.

The payback period of 10 to 20 years from DR revenue alone makes it a poor standalone investment for most commercial buildings. Where DR works financially is when it is stacked with other value streams: avoided capacity charges through Triad avoidance (historically worth £40 to £60/kW annually, now transitioning under Ofgem's Targeted Charging Review), time-of-use tariff optimisation, and battery storage dispatch. The Combined revenue from stacked services can reach £50 to £80/kW, bringing payback periods below five years.

The reality: demand response generates meaningful revenue only when combined with broader energy flexibility strategies. Standalone DR participation rarely justifies the investment for commercial buildings below 1 MW of flexible capacity.

Myth 3: LED Retrofits Always Pay Back in Under Two Years

LED lighting retrofits are often presented as the simplest, most reliable energy efficiency measure with guaranteed payback within 12 to 24 months. For many applications this holds true, but the blanket claim obscures important variations. The Lighting Industry Association's 2025 UK retrofit database covering 2,800 commercial LED projects found that payback periods ranged from 1.2 to 5.8 years, with a median of 2.4 years (LIA, 2025).

Projects at the shorter end of the payback range involved replacing T8 fluorescent fixtures in spaces with high operating hours (warehouses, retail, hospitals) where electricity costs were above £0.20/kWh. Longer payback periods were associated with replacing already-efficient T5 fluorescent systems, spaces with low operating hours (conference rooms, infrequently used offices), and buildings with lower electricity tariffs. Additionally, projects that included advanced lighting controls (daylight harvesting, occupancy sensing, tunable white) added 40 to 60% to project costs while delivering only 10 to 15% additional energy savings beyond the lamp replacement itself.

The reality: LED retrofits are among the most reliable efficiency investments, but payback periods vary significantly by application. The sub-two-year payback is realistic for high-hour, high-tariff applications replacing older technology but should not be assumed across all building types and usage patterns.

Myth 4: Heat Pump Efficiency Claims Apply Equally Across All UK Building Types

Heat pump manufacturers cite coefficients of performance (COP) of 3.5 to 4.5, meaning every unit of electricity input delivers 3.5 to 4.5 units of heat. These figures are accurate under test conditions but require context in real UK buildings. The Electrification of Heat Demonstration Project, a BEIS-funded study monitoring 742 heat pump installations across the UK, found in-situ seasonal performance factors (SPF) averaging 2.8 for air-source heat pumps and 3.2 for ground-source units (DESNZ, 2025).

Performance varied significantly by building type. Well-insulated new-build homes achieved SPFs of 3.5 to 4.0, close to manufacturer claims. Older buildings with poor insulation and high-temperature heating systems (standard radiators requiring 65 to 75 degree Celsius flow temperatures) achieved SPFs of only 1.8 to 2.5, barely better than direct electric heating in the worst cases. The Energy Saving Trust's 2025 guidance emphasises that heat pumps in unrenovated pre-1960s UK housing stock typically require fabric improvements costing £10,000 to £25,000 before the heat pump can operate at its design efficiency.

The reality: heat pumps deliver excellent efficiencies in buildings with good insulation and low-temperature heating distribution, but installing them in unrenovated older buildings without addressing fabric performance first produces disappointing results and undermines the economic case.

What's Working

Industrial demand response at scale is delivering real value. UK industrial sites participating in National Grid ESO's Short Term Operating Reserve and Dynamic Containment services routinely earn £40 to £70/kW annually from flexible loads such as cold stores, water treatment plants, and electric arc furnaces. Flexitricity, a leading UK DR aggregator, manages over 1.5 GW of flexible capacity from more than 3,500 industrial and commercial sites, demonstrating that aggregated flexibility can operate reliably at grid scale.

Whole-building retrofit programs such as Energiesprong, originally developed in the Netherlands and now operating through 14 projects in Nottingham and other UK social housing contexts, deliver guaranteed energy performance through integrated facade, roof, and heating system upgrades. Monitored data from Nottingham's completed projects show 60 to 70% energy demand reduction with 30-year performance guarantees backed by the installer (Energiesprong UK, 2025).

Corporate power purchase agreements (PPAs) with embedded demand flexibility are an emerging model. Companies such as Tesco and BT have integrated behind-the-meter flexibility into their renewable energy procurement strategies, using on-site battery storage and load shifting to maximise self-consumption of contracted renewable generation while providing grid services.

What's Not Working

Behavioural energy reduction campaigns in commercial buildings consistently underperform expectations. A meta-analysis by University College London covering 28 UK workplace energy behaviour programs found average sustained savings of 2 to 4%, far below the 10 to 15% often projected by programme designers (UCL Energy Institute, 2025). Savings typically peaked at 6 to 8% in the first three months before reverting toward baseline as novelty wore off and competing workplace priorities reasserted themselves.

Display Energy Certificates (DECs), mandatory for UK public buildings over 250 square metres, have not driven the improvement trajectory anticipated when introduced. Analysis by the UK Green Building Council found that 43% of public buildings showed no improvement in DEC rating over a five-year period, and 18% actually deteriorated (UKGBC, 2025). The penalty regime for non-compliance is weak, and the certificates lack the financial consequence needed to motivate capital investment.

Small and medium enterprise (SME) engagement in energy efficiency remains stubbornly low. Despite ESOS (Energy Savings Opportunity Scheme) audits identifying an average of £56,000 in annual energy savings per qualifying enterprise, the Federation of Small Businesses reports that only 22% of SMEs implement the recommendations within two years of receiving their ESOS report (FSB, 2025).

Key Players

Established: National Grid ESO (system operator procuring demand response services), Siemens Smart Infrastructure (building energy management systems and controls), Schneider Electric (EcoStruxure building automation platform), Daikin (heat pump manufacturing with strong UK market share), SSE Energy Solutions (energy efficiency services and retrofit delivery)

Startups: Flexitricity (demand response aggregation across 3,500+ UK sites), Passiv (AI-driven building energy optimisation for commercial portfolios), Verv (disaggregated energy monitoring using machine learning), Hometree (residential heat pump installation and maintenance platform), Demand Logic (analytics platform identifying BEMS faults and optimisation opportunities)

Investors: Amber Infrastructure (UK social housing retrofit investment), Green Investment Group (energy efficiency project finance), Legal & General Capital (net zero housing and retrofit investment), Triple Point Energy Efficiency Infrastructure Company (listed fund investing in UK energy efficiency projects)

Action Checklist

• Benchmark current building energy performance using Display Energy Certificate or NABERS UK methodology before setting improvement targets
• Require BEMS vendors to provide measurement and verification protocols with savings guarantees tied to actual metered performance, not modelled estimates
• Evaluate demand response revenue potential across all available services (capacity market, balancing services, Triad avoidance, time-of-use optimisation) before assessing viability
• Prioritise LED retrofits in high-operating-hour spaces with older lamp technology where sub-three-year payback is most likely
• Commission building fabric assessments before heat pump installation in pre-1990 buildings to ensure heating distribution can operate at low flow temperatures
• Establish continuous commissioning processes for BEMS to prevent set point drift and sustain savings beyond the first 18 months
• Stack efficiency measures with demand flexibility and on-site generation to maximise whole-building financial returns

FAQ

Q: What energy savings should a UK commercial building realistically target from a BEMS upgrade? A: Based on monitored data from over 340 UK commercial buildings, plan for 12 to 18% energy reduction as a realistic median outcome. Budget for ongoing commissioning and performance monitoring, which typically costs £3,000 to £8,000 annually but prevents the savings degradation that affects 60% of installations. The 30 to 40% figures quoted by vendors are achievable only in poorly performing buildings receiving comprehensive upgrades with dedicated facilities management support.

Q: Is demand response worth pursuing for commercial buildings under 500 kW? A: Standalone demand response revenue at current UK market rates (£8 to £25/kW) is unlikely to justify the investment for buildings below 500 kW of flexible capacity. However, if the building also has on-site battery storage, an electric vehicle charging fleet, or exposure to half-hourly settled electricity tariffs, the combined value of demand flexibility across multiple revenue streams can make participation worthwhile. Work with an aggregator to model stacked revenues before committing.

Q: How should sustainability professionals evaluate heat pump performance claims? A: Ask for seasonal performance factor (SPF) data from monitored UK installations in comparable building types, not laboratory COP figures. For existing buildings, insist on a heat loss assessment at design winter conditions (minus 3 degrees Celsius for most of England, minus 5 degrees Celsius for Scotland) and confirmation that the heating distribution system can operate at flow temperatures of 45 degrees Celsius or below. If the building requires flow temperatures above 55 degrees Celsius, budget for radiator upgrades or fabric improvements before the heat pump delivers its design efficiency.

Q: What is the most cost-effective first step for a UK office building seeking to reduce energy consumption? A: Commission a half-hourly energy data analysis to identify baseload waste: energy consumed outside occupied hours. The Carbon Trust estimates that 30 to 40% of commercial building energy consumption occurs during unoccupied periods due to systems running 24/7 without need. Addressing baseload waste through controls optimisation is typically the lowest-cost, fastest-payback measure, often costing less than £5,000 to implement and delivering 8 to 15% savings within weeks.

Sources

• Carbon Trust. (2025). Commercial Building Energy Survey 2025: Energy Performance Benchmarks for the UK Office and Retail Sectors. London: Carbon Trust.
• HM Government. (2025). Energy Efficiency Taskforce: Interim Report on the Pathway to 15% Demand Reduction by 2035. London: DESNZ.
• UK Energy Research Centre. (2025). The UK Energy Efficiency and Flexibility Market: Size, Structure, and Growth Projections. London: UKERC.
• Better Buildings Partnership. (2025). Real Performance, Real Savings: Analysis of BEMS Upgrades Across 340 UK Commercial Buildings. London: BBP.
• Chartered Institution of Building Services Engineers. (2024). Building Controls Performance in Practice: A Five-Year Review of BEMS Installations. London: CIBSE.
• Association for Decentralised Energy. (2025). UK Demand Response Market Report: Revenue Benchmarks and Participation Economics. London: ADE.
• Lighting Industry Association. (2025). LED Retrofit Performance Database: Payback Period Analysis of 2,800 UK Commercial Projects. Telford: LIA.
• Department for Energy Security and Net Zero. (2025). Electrification of Heat Demonstration Project: Final Monitoring Report. London: DESNZ.
• UCL Energy Institute. (2025). Behavioural Energy Reduction in UK Workplaces: A Meta-Analysis of 28 Programmes. London: UCL.
• Energiesprong UK. (2025). Nottingham Whole-House Retrofit Programme: Monitored Energy Performance Results. London: Energiesprong UK.