Air intake in the sunspace conservatory floor

Under floor air duct for sunspace conservatory

ABB HRV system

EcoVent HRV system

More than 50% of the heat loss of standard buildings in the UK is caused by infiltration. This issue is particularly relevant given the noise, air pollution and exposed hill slope location of the site.

The following elements were therefore carefully installed and specially sealed:

• Window frames were made with very small tolerances.
• Wood was utilised which doesn’t crack and open-air gaps.
• Sealants such as butyl layers were used to ensure sealing between inner and outer frames.
• Direct wood-brick contacts in the building shell were also avoided. If the wall was not airtight itself, sealant layers such as foils were used.
• Around the external doors the gap was sealed.
• Lock mechanism with small holes, and insulated and double letter slots were used here. All penetrations through walls and ceilings were dense filled with insulation material such as mineral wool.

To ensure that the buildings are very airtight they were pressure tested on completion. In this process, the front door was replaced with a test fan that blows air into the building. The airflow was adjusted to achieve a positive pressurisation of 50 Pa within the dwelling. The lower the air flow necessary to maintain that pressure the tighter the building.

Pressure testing the buildings was a substantial part of the SAP ratings calculation for the buildings. To achieve a low energy standard the hourly natural air change should be less than 0.1/hour. To assure the air tightness pressure testing with blower door has been made after construction completion.

The ventilation strategy for the project was controlled ventilation using mechanical plant with extract and supply systems. Whole house heat recovery systems (WHHRV) have been used so that the buildings can be sealed tight, and negate the need to provide background trickle ventilation. These systems also contribute towards improved air quality, particularly relevant near a motorway, as the systems filter the air, as well as having intakes on the leeward side of the buildings, away from the motorway.

Two ventilation systems:
The design criteria for the ventilation systems are based on:
WC Rooms:       4 air changes/hour
Bathrooms:        15 l/s or minimum of 4 AC/h
Kitchen:             30 l/s or minimum of 1 AC/h

The WHHRV provide supply air to all bedroom and living room spaces, and extract from the kitchen and all bathrooms. The heat recovery unit includes separate supply and extract fans, and a plate heat exchanger to recover waste heat from the extracted air.

Two systems have been used, one manufactured by ABB, and the other by EcoVent. This will give an opportunity to see how a standard WHHRV will perform in comparison to the latest European technology.

Seven heat recovery ventilation systems have been realised according to normal UK standard using ABB technologies. And for comparison two of the heat recovery ventilation systems have been delivered from the Danish EcoVent company. These have been installed in A-type houses. The EcoVent HRV systems are developed with a low electricity consumption and also low noise level.

The HRV unit from EcoVent is a LS 400 model, which was specially developed for the purpose and is installed by clicking three parts together so it was very easy to fit into the closet in Portsmouth.

More than 50% of the heat loss of standard buildings in the UK is caused by infiltration. This issue is particularly relevant given the noise, air pollution and exposed hill slope location of the site.

The potential for excessive solar heat gain from the conservatories in the summer months was a design concern. To avoid overheating of the conservatories and adjacent rooms, the conservatories are cooled by supplying fresh air filtered through an earth duct buried underneath the slab. The air is supplied via high performance Photovoltaic powered DC centrifugal fans. Some of the larger conservatories also incorporate PV powered extract fans, which are located at high level on the opposite side of the room to the floor mounted supply grille. This should also maximise passive stack assistance. The fresh air intakes are again located on the leeward side of the house, to cut out noise and pollution from the motorway.


Suppliers of technology:

EcoVent
Rudolfgardsvej 19
DK-8260 Viby J
Phone: +45 70 23 88 02
Fax: +45 70 23 21 80
e-mail: info@ecovent.dk
www.ecovent.com

ABB Ltd
Daresbury Park
Daresbury
Warrington WA4 4BT
Phone: +44 1925 741111
e-mail contact@gb.abb.com