The question of whether an A++ home specifically requires a heat recovery unit often arises only when an equipment model is already being selected. Yet the energy class, ventilation needed for hygiene and the purchase of a particular appliance are different questions. The answer must be based on the regulations and design applicable to the particular building, not a sales slogan. Neither an appliance label nor a general promise that it 'meets A++' confirms compliance of the whole home in itself.
Distinguish the requirement's wording
A condition in legislation that applies when a system is installed is not the same as a universal requirement to install that particular system. This distinction is illustrated by the archived VTPSI consultation on A++ and heat recovery. However, its date matters: this is a consultation based on earlier regulations, not an individual decision for your home or a substitute for checking the current edition.
Information on current editions must be checked in the STR 2.01.02:2016 register. In the text checked on 2026-10-26, consolidated from 2026-01-01, the condition concerning heat recovery unit performance in table 1, subparagraph 7.3, is linked to an installed mechanical ventilation system with heat recovery. That subparagraph alone is not a general instruction for every A++ building to buy a particular appliance. However, it is also insufficient by itself to decide that a different ventilation approach will ensure compliance of the whole home.
The designer must check the complete set of requirements applicable to the particular property. This information text does not give the same legal conclusion for every building or transfer the figures stated in the archived consultation into the current design. It is necessary to check not just the selected extract from the provision, but also its conditions of application and the other related documents.
Why an older explanation is insufficient
Regulation editions change. The Ministry of Environment notice of 2026-01-09 discusses STR amendments that came into force at the beginning of the year. The practical principle is simple: when you find an old response from an authority, first check its date and scope of application. An article at the top of the search results does not necessarily reflect the project being assessed today.
It is also essential to know the building's use and the circumstances of construction. Requirements for different properties should not be transferred from one to another solely because the energy class has the same letters. A newly built detached house and a non-residential building with a particular use are not automatically equivalent cases. If the applicable edition or transitional conditions are unclear, an explanation from the responsible designer is needed.
What the house design should state
The ventilation design must specify how outdoor air is supplied to occupied rooms and how used air is removed. Air quantities, routes, transfer between rooms, controls and maintenance all need to be understood. At the same time, the energy calculation must use data corresponding to the solution. Two separate tables that do not agree with one another do not help achieve a reliable result.
If the design specifies a mechanical system with heat recovery, replacing it with another solution is not merely choosing a cheaper appliance. It is necessary to assess whether the energy and other performance indicators, design solutions or required approvals change. A purchasing decision should not be made before these consequences are understood. A seller's verbal promise is not a document revising the design.
Equipment data is not a whole-house guarantee
A heat recovery performance figure has defined test conditions, while fan electricity consumption also depends on the operating point. One catalogue percentage therefore does not tell you how the system will operate with particular ducts and filters. The designer needs reliable data for the particular model, followed after installation by a check of the specified airflows.
It is also important not to rely solely on a claim that a unit is 'suitable up to a certain floor area'. The required air quantity relates to the rooms and their use, while the appliance's capability relates to actual resistance. This distinction applies regardless of energy class. An expensive model will not compensate for an undesigned airflow route or incorrect installation.
Illustrative example: two proposals for a home
Suppose an owner has an A++ house design and receives two proposals. One provides a complete heat recovery ventilation system; the other provides only extract fans and air inlets. A lower price does not in itself prove that the second option is bad, but it cannot be regarded as equivalent solely because both use the general word 'ventilation'. The precise design solution must be compared.
The owner gives both options to the designer and the energy performance expert. They must identify what information is missing and whether the design and calculation need to be changed. Only then can equipment, installation and operation be compared on a sound basis. Otherwise, savings in a quotation may turn into additional redesign work or uncertainty when completing the building.
Which documents should you request?
Start with the current ventilation section of the design and the assumptions in the energy calculation. Add technical documents for the particular appliances proposed, operating-point data and the system layout. If the solution is changed, it must be clear who assessed and approved that change under the procedure for your property. An online shop page alone is insufficient.
After the work, keep balancing data, settings and maintenance instructions. If the documents specify one appliance but another has been installed, the difference must be resolved rather than ignored. The actual condition and the documents handed over must correspond to one another. This matters not only for certification, but also for later maintenance.
If sellers disagree
Ask each seller to provide not just an opinion, but a specific reference to the applicable requirement and its edition. Then refer the question to the design author. Do not try to choose the more convenient general answer or treat it as permission to depart from the design. An equipment seller may know their product very well, but responsibility for the whole property's energy and other design solutions must be clearly assigned.
It is worth obtaining agreement in writing and retaining the particular model and layout version. If the proposal is changed later, the old agreement does not automatically cover the new option. It is convenient to keep the design extract, data sheet and responsible specialist's explanation in one file. The decision will then remain understandable not only on the purchase date, but also during installation, testing and completion. The price comparison is then based on the same clear brief.
What this article does not promise
This article does not provide an individual legal conclusion or an energy performance certificate. Its aim is to help distinguish questions about regulations, design and products, and to request appropriate evidence. A link to an older consultation cannot be used as permission to abandon a system specified in the design on your own initiative. Equally, nobody should be told without checking that a particular manufacturer is required for everyone.
Read about selecting the air quantity here. In your enquiry, include an extract from the design and the proposed model, rather than only the home's energy class. The discussion will then begin with the actual solution and its verification, rather than conflicting general promises.
Information sources
You can read the explanation without leaving this page. The original document opens only when you choose its link.