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Aerotermia Ibizaa Climai Group project

Draft pending review by Climai Group

Ventilation with heat recovery (MVHR) in Ibiza

In short

Balanced mechanical ventilation renews the air in the home and, with a heat recovery unit, uses the temperature of the outgoing air to temper the incoming air. In a home heat recovery is not compulsory, but it improves comfort and reduces the energy lost through ventilation.

Author: Climai Group technical teamTechnical review: [DATO PENDIENTE: técnico RITE de Climai Group]Updated:

What is ventilation with heat recovery?

It is a system that renews the air in the home with fans and ducts, without relying on opening windows. In the balanced (two-way) version, a unit brings in outdoor air and extracts indoor air, and between the two flows there is a heat recovery unit: an exchanger that passes the temperature of the outgoing air to the incoming air without mixing them.

SystemHow it worksRecovers temperature
Natural or hybrid ventilationOpenings and ducts; in hybrid systems, mechanical extraction when neededNo
Single-flow mechanicalA fan extracts air from bathrooms and kitchen; air comes in through openingsNo
Balanced mechanical with heat recoveryA unit supplies outdoor air and extracts indoor air through ductsYes

What does the Building Code require in a home?

Basic Document HS 3 (indoor air quality) requires homes to have a general ventilation system, hybrid or mechanical, in which air flows from dry rooms to wet rooms:

  • Supply in dining rooms, bedrooms and living rooms.
  • Extraction in toilets, kitchens and bathrooms.
  • Transfer openings between supply rooms and extraction rooms.

The RITE (IT 1.1.4.2.1) accepts the HS 3 indoor air quality requirements as valid for homes.

Is heat recovery compulsory?

In a normal home, no. The RITE requires energy to be recovered from exhaust air when the mechanically extracted flow exceeds 0.28 m³/s, far more than a house needs.

Even so, in a well-insulated home with a heat pump, heat recovery makes sense: without it, every cubic metre of renewed air takes away the heat (or coolness) the heat pump has produced.

Why does it suit a heat pump?

  • Tighter homes, fresh air. Modern windows and insulation reduce air leakage; mechanical ventilation renews the air without opening windows.
  • Less loss when ventilating. The recovery unit keeps part of the temperature the heat pump has produced.
  • Steady comfort. With underfloor heating and heat recovery ventilation, the home keeps an even temperature without cold draughts.
  • Filtration. Incoming air passes through filters, which helps with dust and pollen.

What does the installation need?

ElementWhat it is
Ventilation unit with heat recoveryFans, exchanger, filters and controls
Supply and extract ductsThrough false ceilings, raised floors or service shafts
Supply and extract ventsSupply in dry rooms; extraction in bathrooms and kitchen
Outdoor air intake and exhaustKept apart so exhaust air does not come back in
Bypass (depending on the unit)To ventilate without recovery when outdoor air is more pleasant

In a new build it is designed with the project; in a renovation the challenge is routing the ducts. We study it at the visit together with the heat pump: request a quote and mention you are interested in ventilation.

Frequently asked questions

Is mechanical ventilation compulsory in a home?

The Building Code (DB HS 3) requires homes to have a general ventilation system, which may be hybrid or mechanical. Heat recovery, however, is not compulsory in a normal home.

When does the RITE require heat recovery?

When the air mechanically exhausted outdoors exceeds 0.28 m³/s. In a normal home the flow is far below that, so heat recovery is a comfort and savings decision.

Can I still open the windows?

Yes. Mechanical ventilation renews the air even with the windows closed; opening them is still possible, but no longer needed to renew the air.

Does the heat recovery unit also cool in summer?

It does not produce cooling: it recovers part of the temperature of the outgoing air. In summer, with the home cooled by the heat pump, it helps the incoming air arrive less hot. Many units have a bypass to ventilate without recovery on cool nights.

Does it remove humidity?

Renewing the air helps remove moisture from bathrooms and the kitchen. Lowering humidity in summer requires dehumidification, for example with fan coils or a dehumidifier; some (enthalpy) recovery units also transfer part of the humidity.

What maintenance does it need?

Mainly replacing or cleaning the filters as often as the manufacturer specifies, and checking the unit and the supply and extract vents.

Can it be installed in a renovation?

Yes, but the ducts need a route (false ceilings, cupboards, service shafts). In a new build it is much easier because it is planned from the design stage.

Sources

  1. Spanish Building Code, Basic Document HS Health (section HS 3, Indoor air quality) · Ministry of Housing and Urban Agenda · codigotecnico.org ·
  2. Royal Decree 1027/2007, Regulation on Thermal Installations in Buildings (RITE), IT 1.1.4.2 · BOE ·

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