Title: Heat Pump Efficiency vs. Electric and Gas Heating: Choosing the Right System for Sustainable Comfort

Introduction

As energy efficiency becomes a critical priority in both residential and commercial buildings, the choice of heating systems plays a central role in reducing operational costs and carbon emissions. In this article, we compare different heating solutions—Exhaust Air Heat Pumps (EAHPs), low-powered heat pumps, direct electric heating, and gas boilers with MVHR—to explore which systems provide the best balance of efficiency, cost-effectiveness, and sustainability.

For developers, mechanical consultants, and building owners, understanding the performance of each system under real-world conditions can lead to better decisions when designing nearly zero-energy buildings (nZEB) and minimizing energy bills.

Reference building here is a 70m2, 2 bed with a heat loss of approx. 2.2kW at -3/21

1. The Efficiency Challenge: EAHPs vs. Low-Powered Heat Pumps

Exhaust Air Heat Pumps (EAHPs) are designed to recover heat from the air extracted from a building’s ventilation system. These systems are effective in maintaining indoor air quality while minimizing energy wastage, making them popular in modern energy-efficient buildings. However, system performance depends heavily on the size of the compressor, airflow, and the climate.

Key Insights from EAHP Systems:

• High Efficiency Potential: EAHPs can achieve significant energy savings by extracting heat from exhaust air. In a system with an airflow of 21 l/s, the energy extracted from the air can reach 1.33 kW, with a total delivered energy of 2.49 kW when factoring in the compressor input.
• Optimal Sizing Matters: Many EAHPs are fitted with oversized compressors, leading to inefficiencies in low-demand situations. Right-sizing the compressor to match the building's actual heating needs can significantly improve the Coefficient of Performance (COP), allowing the system to deliver more heat for less energy input.

In contrast, low-powered heat pumps, which are often undersized to minimize installation costs, can struggle to meet the heating demands of a building. These systems often rely on backup electric heaters to cover the gap, which leads to:

• Lower Efficiency: When outdoor temperatures drop, the reliance on electric heaters drives up energy consumption.
• High Operational Costs: Electric elements add significantly to winter heating bills, resulting in costs that can reach up to €3,175.50 annually in some cases.

2. Direct Electric Heating: A Short-Term Solution with Long-Term Costs

Direct electric heating, while easy to install and maintain, comes with significant drawbacks in terms of energy efficiency and operational costs. While these systems have 100% efficiency (all input electricity is converted into heat), the cost of electricity is much higher than alternative sources, such as natural gas or renewable energy.

For example, a standard electric radiator system operating with MVHR for heat recovery may consume up to 8,920 kWh annually for space heating. At an electricity cost of €0.30/kWh, this translates into annual heating costs of €2,408.09, and even with solar PV panels reducing some of the demand, the operational costs remain high.

Downsides of Electric Radiators:

• High Running Costs: Direct electric heating systems, particularly in colder climates, can lead to exorbitant energy bills, especially when electricity prices are high.
• Inflexibility: Unlike heat pumps, which can modulate their output and use ambient heat, direct electric heating relies entirely on expensive electricity to provide warmth.

3. Gas Boilers with MVHR: A Traditional Approach with Lower Costs but Higher Emissions

Despite the push towards renewable energy and heat pumps, gas boilers continue to be a popular heating choice, especially when combined with Mechanical Ventilation with Heat Recovery (MVHR) systems to capture heat from the exhaust air.

While gas boilers have higher CO₂ emissions than heat pumps, they offer relatively low operational costs compared to electric systems. In our analysis, a gas boiler with 90% efficiency consumes around 13,116 kWh annually, resulting in heating costs of €1,797. When you factor in DHW (Domestic Hot Water), the total cost rises to approximately €2,519.02 annually.

Advantages of Gas Boilers with MVHR:

• Lower Operational Costs: With natural gas being cheaper than electricity, gas boilers often provide more affordable heating.
• Reliable Performance: Gas boilers are well-established, reliable, and capable of providing consistent heating even during the coldest months.

Disadvantages:

• High Carbon Emissions: Gas boilers contribute significantly more CO₂ emissions than heat pumps or electric systems. In a typical system, emissions can reach 3,402.9 kg CO₂ per year.
• Long-Term Sustainability: As global policies shift towards decarbonization, the reliance on fossil fuels for heating is becoming less viable in the long term.

4. The Path Forward: Balancing Costs, Efficiency, and Sustainability

When comparing EAHPs, low-powered heat pumps, electric heating, and gas boilers with MVHR, the ideal system depends on a combination of factors including building size, budget, and sustainability goals.

Key Takeaways:

• Exhaust Air Heat Pumps (EAHPs) offer the best balance of energy recovery and sustainability, especially when paired with a right-sized compressor and optimized airflow. With annual heating costs of €1,284.53, these systems are both cost-effective and environmentally friendly, emitting around 1,211.7 kg of CO₂ annually.
• Low-powered heat pumps often struggle with undersized compressors and over-reliance on electric heating, leading to higher costs and emissions. While initially cheaper, they result in total annual costs of €3,175.50, much higher than other options.
• Direct electric heating remains an expensive option, particularly in colder climates with high electricity prices. Even with MVHR and PV systems, the total annual costs can reach €2,675.95 with substantial carbon emissions.
• Gas boilers with MVHR provide a lower-cost heating solution but are less sustainable in the long run due to their carbon footprint. While gas prices are lower than electricity, the emissions impact is significant, making it less suitable for future nZEB goals.

Conclusion: Choosing the Best System for Your Needs

For those aiming to meet nZEB standards or simply reduce their operational costs and environmental impact, Exhaust Air Heat Pumps (EAHPs) stand out as a balanced, cost-effective solution. By ensuring the compressor size matches the building’s demand, and optimizing airflow, you can achieve a high COP, reducing both energy costs and CO₂ emissions.

As building regulations tighten and energy prices fluctuate, the choice of heating system will play a vital role in ensuring long-term sustainability and affordability. For building owners, developers, and consultants, making the right choice today will yield benefits for years to come.

Call to Action:

At RBSi, we specialize in energy-efficient heating systems, including heat pumps and mechanical ventilation solutions. If you’re looking for expert advice or tailored systems to meet your building’s needs, connect with us today. Let’s work together to build a more sustainable and energy-efficient future.