---
id: "VOLT-HOME-WP-050"
title: "Should a household place only flexible heating load on a dynamic tariff?"
slug: "should-a-household-place-only-flexible-heating-load-on-a-dynamic-tariff"
description: "A split-load scenario measures wholesale price exposure when 35% of heating energy is dynamic and the remaining 65% is fixed."
published: "2026-08-30"
cluster: "Heat pumps and thermal storage"
status: "measured"
evidence: "/research-data/home-papers/should-a-household-place-only-flexible-heating-load-on-a-dynamic-tariff.json"
figure: "/research-media/home-papers/should-a-household-place-only-flexible-heating-load-on-a-dynamic-tariff.webp"
figure_alt: "Chart for Should a household place only flexible heating load on a dynamic tariff?: price exposure retained when only 35% of heating load is dynamic, shown as fixed share, dynamic share."
source_ids:
  - "energy-buildings-heat-pump"
  - "nordic-cost-comfort"
  - "acer-retail-2025"
  - "ec-retail-flexibility-2026"
  - "dynamic-tariff-viability"
peer_reviewed: false
---

# Should a household place only flexible heating load on a dynamic tariff?

## Abstract

Splitting heating load between fixed and dynamic price exposure can limit both opportunity and risk, but the appropriate split depends on the household and contract. This working paper measures a declared scenario in which 35% of heating energy is flexible and dynamically exposed while 65% remains fixed. Across 2,367 matched temperature-price observations, mean retained dynamic price exposure is 77.71315727925644 EUR/MWh-load, calculated as 35% of the absolute recorded daily mean day-ahead price. No uncertainty interval is reported for this estimand. The point estimate describes exposure, not savings, risk-adjusted value, or an optimal hedge. No fixed-tariff price is supplied, and no counterfactual whole-load bill is calculated; therefore, the evidence cannot answer “should” as a universal recommendation. It supports the narrower conclusion that isolating a declared flexible share mechanically limits the amount of heating energy exposed to dynamic wholesale prices. Complete retail terms, flexibility constraints, COP, comfort, and risk preference are required for a household decision. The reduced-order synthetic scenarios are not building simulations, customer telemetry, savings claims, or retail bills.

## Plain-language answer

The evidence supports splitting flexible and inflexible load as a risk-control concept, but it does not prove that 35% is the right share for a household. Under the declared split, 35% remains dynamically exposed and 65% is represented as fixed. The resulting mean exposure is 77.71 EUR/MWh-load; no uncertainty interval is reported.

That number is not a bill and does not compare a real fixed-price offer with a dynamic tariff. It simply measures the scale retained after applying the 35% share to absolute daily mean wholesale prices. [ACER and CEER](https://www.ceer.eu/wp-content/uploads/2025/11/ACER-CEER-2025-Retail-monitoring.pdf) provide assigned context for offering consumers a range of contract choices. The [dynamic-tariff viability study](https://doi.org/10.1016/j.adapen.2024.100174) provides assigned context for enabling costs and household asset differences. The correct split remains a contract- and household-specific choice.

## Research question

The registered question asks whether a household should place only flexible heating load on a dynamic tariff. We operationalise the flexible share as 35% of heating energy and measure the absolute wholesale price exposure retained by that share. The complementary 65% is labelled fixed in the figure.

This is an exposure decomposition, not a tariff recommendation. The analysis does not know the price of the fixed contract, whether suppliers permit load-level splitting, or how the meter would allocate consumption. It does not optimise a hedge ratio, estimate risk aversion, or simulate a household’s feasible heat schedule. It asks what a declared partial-exposure rule does to the scale of wholesale price exposure.

## Data and provenance

The evidence has publication cutoff 2026-08-30T00:00:00Z. It records daily-price coverage from 2021-01-01 through 2026-08-29, detailed interval coverage from 2025-10-01 through 2026-08-29, and long-history coverage from 2015-01-01 through 2026-08-29. Its family-level source-table contract contains `day_ahead_prices`, `zone_temp_weighted`, `zone_load`, `generation_mix`, and `forecasts`.

The operative panel contains 2,367 daily price summaries paired to available population-weighted zone temperatures. For every row, the calculation uses the absolute recorded daily mean price and multiplies it by 0.35. No household heating quantity, consumption profile, tariff bill, or meter assignment is observed.

The analysis ran in a SELECT-only transaction with a 180-second statement timeout. Provenance hashes are snapshot `7e97489fc8528c8cc8c38830e05b48d949ce1f67b98575dff26f5d7c321e4c67`, analysis code `57c57de79cdab2b5b6d6c54c485cb5162598c5ba0b0bfe995da40d75e6c52ba9`, protocol `adb36bf6b447af9f96339249b8becaefc20422499cca1977242866347a97bd4b`, registry `7bcb91d7476d0a69fe9fa75a5c7782f8117e0153f82f9112b7e1d307d3943717`, and source registry `07949550ac443ff673fda5c0209b99f137544f3ffecf6775f109bb9d09663bd6`, all SHA-256. The evidence and figure hashes are `4482aecc6dd917bd0befcda6429763de1c38fedb794c69748c478ed1a5fe3741` and `0846bae842006eac0bafefa205c6e30ae5190fd0cfe3ae6ca8eeeae4a181ed62`.

The assigned [European Commission communication](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A52026DC0115) concerns retail prices and flexibility. The [Energy and Buildings source](https://doi.org/10.1016/j.enbuild.2023.113257) provides context on thermal flexibility under tariff designs, and the [Nordic cost–comfort source](https://doi.org/10.3390/en18215568) provides context on multiple household objectives. None supplies the 35% coefficient or the result.

## Method

For each matched observation with daily mean price \(P\), the analysis calculates `abs(P) × 0.35`. Taking the absolute value means negative and positive daily mean prices both contribute positive exposure magnitude. The primary result is the arithmetic mean of those transformed values.

The figure reports the load split itself: 65 fixed and 35 dynamic. It does not display a fixed-tariff cost or a savings comparison. The interpretation in the evidence is that separating flexible from inflexible load limits both upside and tail exposure. That interpretation is qualitative because the calculation contains no explicit tail metric or fixed-price counterfactual.

The preserved assumptions are synthetic heat demand, no customer telemetry, COP sensitivity declared per paper, wholesale energy only, and a 35% flexible heating-energy share. COP is not applied. There is no thermal state, comfort band, heating-energy volume, network charge, tax, supplier margin, VAT, or fixed tariff price.

The regenerated evidence reports no uncertainty interval for the transformed exposure observations and names the interval method as “not reported for this estimand.” Within-family Holm control applies to inferential claims; this descriptive exposure statistic makes no unadjusted significance claim.

## Results

The mean price exposure retained when only 35% of heating load is dynamic is 77.71315727925644 EUR/MWh-load. The sample size is 2,367 observations. The frozen evidence reports no uncertainty interval for this estimand.

The figure divides the declared load into a 65% fixed share and 35% dynamic share. This split does not establish that exposure falls by exactly 65% relative to a real whole-load dynamic bill because the statistic uses absolute daily mean wholesale prices and no fixed tariff comparator. It does establish the arithmetic scale of the dynamic share under the chosen coefficient.

The result is best read as an exposure budget. A household that exposes only a subset of flexible energy to a dynamic signal constrains how much energy is directly sensitive to that signal. Whether this improves expected cost, worst-case cost, comfort, or welfare is not measured. No “optimal” share is identified.

## Robustness and placebo checks

The 65/35 decomposition is explicit, which prevents the flexible share from being inferred after seeing the result. Applying the coefficient observation by observation before averaging preserves variation in daily mean price magnitude. No bootstrap interval is reported for that transformed distribution.

An algebraic zero-share placebo would produce zero dynamic exposure; a 100% share would retain the full absolute price magnitude. Those endpoints clarify the method but are not separately published evidence arms. No alternative 10%, 25%, 50%, or 75% grid was frozen for this paper, so it would be improper to present one as measured.

There is no fixed-contract placebo, no matched retail-bill comparison, no crisis-period stress, and no household risk-preference model. The use of absolute prices also means the statistic does not distinguish favourable negative prices from adverse positive prices. Within-family Holm control remains applicable to inferential work, while this paper reports no p-value or causal effect.

## Limitations

The key missing input is the fixed side of the proposed split. Without a fixed tariff price, term, fees, exit conditions, and allocation rule, the paper cannot compare total cost. Some retail markets may not permit a household to place only one end use or fraction of load on a separate dynamic contract.

The 35% flexible share is declared, not measured. Actual flexibility depends on building heat loss, thermal mass, hot-water storage, occupancy, comfort, heat-pump power, COP, and weather. Daily temperature and price summaries cannot reproduce a building-specific thermal state.

Absolute daily mean price measures magnitude but discards sign. That is useful for exposure scale and insufficient for expected savings or downside. Daily aggregation also hides intraday price spreads, which are the actual source of scheduling flexibility.

Wholesale energy is not a retail bill. Network charges, taxes, VAT, supplier margin, fixed fees, metering, and consumer protections are excluded. The reduced-order synthetic scenarios are not building simulations, customer telemetry, savings claims, or retail bills. The result is not a recommendation to hedge 65%, expose 35%, or switch tariff.

## Practical implication

A household considering dynamic exposure should first identify which heating energy is genuinely flexible without compromising comfort or hot-water service. It can then compare partial and full exposure under actual retail offers, including all charges and a range of weather and price outcomes.

Where contract structure permits, separating a flexible tranche can be a transparent risk-control design. The controller should cap energy and power, preserve a fixed fallback, and show the user how much load is exposed. The assigned policy sources support broad consumer choice rather than a single contract for everyone; this paper’s result is consistent with that framing but does not prescribe a product.

## Reproducibility

The canonical evidence is `/research-data/home-papers/should-a-household-place-only-flexible-heating-load-on-a-dynamic-tariff.json`; the matching figure is `/research-media/home-papers/should-a-household-place-only-flexible-heating-load-on-a-dynamic-tariff.webp`. The JSON freezes the 35% assumption, primary value, sample size, explicit null interval, coverage windows, source tables, interpretation, limitations, and provenance hashes.

To reproduce, join the frozen daily price summaries to non-null population-weighted zone temperatures. For each of the 2,367 matched rows, take the absolute daily mean price and multiply by 0.35. Compute the arithmetic mean, but do not reconstruct an interval that is null in the regenerated evidence. Keep the 65/35 figure labels and the publication cutoff. Adding a fixed tariff or changing the share produces a new scenario.

Licensing and attribution requirements are documented at `/legal/data-licensing` and [Voltcast data licensing and redistribution](https://github.com/ossedk/voltcast/blob/main/docs/voltcast/LICENSING.md). Any reuse should preserve the wholesale-only and no-customer-telemetry limitations.

## Disclosure

Analysis and drafting were model-assisted; sources, code, assumptions, and evidence hashes are disclosed. This working paper is not peer reviewed. It contains no trading claim and is not trading advice. Volt has no live traders or live capital. It is not financial, tariff, tax, engineering, or equipment-control advice.

## References

- Energy and Buildings. “Assessment of the thermal energy flexibility of residential buildings with heat pumps under various electric tariff designs.” https://doi.org/10.1016/j.enbuild.2023.113257
- Energies. “Exploring Cost–Comfort Trade-Off in Implicit Demand Response for Fully Electric Solar-Powered Nordic Households.” https://doi.org/10.3390/en18215568
- ACER and CEER. “Rewarding flexibility: How retail contract choice can help unlock consumer flexibility.” https://www.ceer.eu/wp-content/uploads/2025/11/ACER-CEER-2025-Retail-monitoring.pdf
- European Commission. “Communication from the Commission on the Citizens Energy Package.” https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A52026DC0115
- Advances in Applied Energy. “Assessing the conditions for economic viability of dynamic electricity retail tariffs for households.” https://doi.org/10.1016/j.adapen.2024.100174