Peak Shaving Heating: Standby, Startup and Simultaneity
Electric heating with heat pumps, infrared panels, or electric boilers is rapidly becoming popular. However, at the same time, the electricity grid in many regions is congested, and tariffs often vary by the hour. Grid-friendly heating means planning your heat use smartly, taming peak power, and limiting standby losses.
In this guide, we discuss the three levers that have the greatest combined effect on your efficiency: standby, startup, and simultaneity. By creating smarter Flows around all three, you can start optimizing immediately in Homey—without losing any comfort.
Why Peak Shaving Matters
Peak shaving is simply the reduction of the maximum power demanded at any single moment. It helps protect fuses, distribution boards, and main connections, while also reducing capacity costs where applicable and preventing you from landing in expensive dynamic or peak-hour tariffs.
Moreover, heat pumps run more efficiently when they can operate for longer periods and more steadily. By cutting peaks and utilizing the "valleys" in energy prices, you shift energy consumption over time without making your home colder. In this strategy, the thermal mass of your floors, walls, and water buffers acts as your hidden battery.
Eliminating Standby and Parasitic Losses
Standby loss refers to the energy wasted when your heating system is "waiting" to work. This includes circulation pumps that run when no heat is needed or buffer tanks that lose heat through poor insulation. Every watt lost here is a "parasitic" draw that raises your baseline consumption.
Homey can eliminate these losses by coordinating your pumps with your zone valves. Instead of a pump running 24/7, a simple Flow can ensure it only activates when a room actually calls for heat. Additionally, increasing the "hysteresis" or temperature margin in Homey prevents the system from waking up to fix a tiny 0.2°C drop. Allowing a wider margin lets the system rest longer, which significantly reduces unnecessary wear.
Managing Startup and Inrush Currents
The moment a heat pump starts is when it demands the most power. This "inrush current" can create massive spikes that stress your home's circuitry and trigger higher peak-tariff charges. Managing this startup phase is critical for a stable, grid-friendly home.
You can use Homey to "soft-start" your home’s climate by using gradual setpoint changes. Instead of jumping from 18°C to 21°C at 6:00 AM, Homey can increase the target by 0.5°C every 30 minutes. This prevents the heat pump from rushing to its maximum, least efficient power level. If you have multiple heating zones, you can sequence them so the living room starts first and the bedrooms follow 40 minutes later, spreading the electrical load over time.
Reducing Simultaneity and Peak Shaving
Simultaneity is the biggest threat to your home's electrical capacity. If your heat pump, electric boiler, and EV charger all kick in at the same time, you create a massive power peak. The goal of peak shaving is to "flatten" this curve by prioritizing and staggering these heavy loads.
Homey acts as a digital air traffic controller for your appliances. You can create a "Peak Guard" Flow that monitors your total household consumption. If the total power exceeds a certain threshold, Homey can automatically throttle your EV charger or pause the heat pump’s auxiliary heater. Because your floors and walls act as a thermal battery, pausing the heat for 20 minutes to cook dinner won't affect your comfort, but it will keep your power profile low and stable.
Monitoring Efficiency with KPIs
To maintain a grid-friendly home, you need to track specific Key Performance Indicators (KPIs). Homey can provide a weekly digest of your maximum 15-minute power peaks and the total number of compressor starts. If you notice your peaks are consistently high, it is a signal to adjust your simultaneity rules.
By using Homey to shift heavy loads to sunny hours or low-tariff periods, you utilize your home's thermal mass effectively. This proactive approach turns your house into a smart, responsive part of the energy grid. You get the benefit of lower bills and a longer-lasting heat pump, while the grid benefits from a more predictable, manageable load.
FAQ
How much can I save with peak shaving?
It depends on your specific profile, but a reduction of 20–40% in peak power is often achievable with planning and settings alone. The financial impact comes from lower use during expensive hours, fewer grid or connection capacity fees, and more efficient operation of the heat source.
Will peak shaving make my house colder?
Not if you use thermal storage and work with small setpoint steps. Preheat 0.5–1.0°C during low-tariff hours, and limit additional heating only during peak hours. Always set a comfort backstop to intervene if the temperature deviation becomes too large.
Do I need a buffer tank?
Not necessarily, but a buffer increases flexibility and reduces starts. With modulating heat pumps and sufficient water content in your floors, you can often do without one. However, if you have many zones that close often or if you see short cycling, a buffer tank is very useful.
How do I prevent EV charging and heating from peaking together?
Use priorities and charge limits. Give heating priority, reduce EV charging to 6–8 Amps during active heat demand, and only resume full charging when heating is at rest. Furthermore, plan charging over multiple cheap hours—not just one.
Does solar irradiation really help?
Yes. Winter sun can add 1–2°C for free in living areas. Use this by shifting preheating later on sunny days and lowering temporary setpoints to avoid temperature overshoot.
Which KPI is most important?
- For grid friendliness: Your maximum quarter-hour peak.
- For efficiency: Average supply/return temperatures and the number of starts per day.
- For comfort: Time spent outside the setpoint. Combine all three for balanced control.
Is the low tariff period always the best time to heat?
Usually yes, but pay attention to grid congestion and comfort. Sometimes it is smarter to heat slightly earlier or later if that reduces peak power and improves COP. The optimum lies in spreading your usage, not stacking it.
How much can I save with peak shaving?
It depends on your specific profile, but a reduction of 20–40% in peak power is often achievable with planning and settings alone. The financial impact comes from lower use during expensive hours, fewer grid or connection capacity fees, and more efficient operation of the heat source.
