TACKLING OVERHEATING IN CITY CENTRE APARTMENTS

Mark Deeney, business development director for Glen Dimplex Heating & Ventilation, explores the challenges faced when heating and cooling modern apartment buildings – and examines a ‘loopy’ new approach which could revolutionise the way we heat multi-occupancy residential buildings.

Current new build dwellings in the UK are at risk of overheating due to a number of factors which include more stringent regulations on air tightness and fabric performance, increased living density, single aspect apartment design and high internal gains. This risk is exacerbated in city centre multi-residential buildings, where internal gains and solar gains can be more significant due to an increased urban living density.

Modern apartment buildings in the UK range from two storey buildings to in excess of 90 storeys and now represent more than 50 per cent of the planned new build housing stock. Currently, there are approximately 500 projects greater than 15 storeys planned for the UK in the next ten years.

Whilst these towers have different design considerations to other apartment or multi-residential buildings, they share some common constraints, which restrict the ability of the designer to successfully adopt passive cooling measures.

Namely, these include:

  • External noise from wind or traffic influencing window operation behaviour
  • Window restrictions due to tower height
  • Concerns about air pollution influencing window operation behaviour
  • Maximisation of the site footprint for lettable floor space
  • High density living space
  • A trend toward centralised heat generation plant
  • Lack of coordinated control for mechanical ventilation and heating technologies

Overheating can be addressed using mechanical cooling via dedicated chiller plant and a chilled water network, but this often masks the symptom without addressing the cause.

BRE identified that the heating networks in some buildings were failing to perform as expected by the designers, which has been anecdotally discussed in other studies, such as the Seagar distillery published by AECOM/CIBSE.

It identified that the heating networks are losing more than 50 per cent of the total energy produced during distribution and predict poorer results in future nearly zero-energy buildings  (NZEB) planned as dwellings for London. This not only causes an increase in the energy consumption of these dwellings but also inadvertently increases corridor and apartment temperatures to unacceptable levels.

Consideration of performance and selection of the distribution system and centralised plant are key areas where a designer can regain control for the building design.

To overcome this issue, the new Zeroth Energy System from Glen Dimplex Heating & Ventilation (GDHV) offers an innovative new approach to heating and cooling city apartments.

By creating a series of ‘energy loops’ within the building, this alternate distribution design will not only save energy but also improve the thermal comfort of the occupants by significantly reducing the corridor temperatures and providing a lower CAPEX option for comfort cooling when compared with a traditional chiller system.

In addition to using conventional, readily available technologies, Zeroth also facilitates a greater opportunity for the capture of waste heat/cool currently inaccessible to the majority of UK buildings.

Work done to date by GDHV has shown an energy network can improve its efficiency from less than 50 per cent to 98 per cent using Zeroth, which equates to substantial energy and monetary savings.

Zeroth Energy System: how it works

The new Zeroth Energy System from Glen Dimplex Heating & Ventilation (GDHV) delivers localised control to provide comfortable temperatures within apartments, reduce overheating in communal areas and ensure residents only pay for the heating or cooling they use.

Those living in modern apartment blocks face a common issue of uncomfortable temperatures and extra costs. This is a direct a result of building heating systems typically having just one option to accommodate all residents. As a result systems ‘run hot’, with communal areas known to top 36°C year round and those with windows receiving direct sunlight broiling in their apartments. Plus, with the costs of heating system losses spread across all residents, they can easily find themselves paying extra for the discomfort.

The Zeroth Energy System overcomes these issues by creating a series of ‘energy loops’ within the building, replacing the high temperature system with a cool, low pressure system, maintained by the building’s central plant room.

With Zeroth, low temperature water flows around the building’s main loop to each apartment, which all have their own ‘mini loop’ where an individual heat pump produces heated or chilled water to the desired temperature. The water can then be passed to fan coils, which deliver warm or cold air into a room through vents in the ceiling or wall, or to underfloor heating, or smart electrical, fan-assisted wet radiators.

Excess heat generated within the apartments is passed back into the main loop. This means the central plant only needs to fill the balance of heating for the entire building, rather than servicing the total heating or cooling requirements of every resident at once. It is more environmentally friendly, as less total energy is required to heat and cool the entire building, and it is far more cost effective, the benefit of which can be passed on directly to residents in the form of lower average heating or cooling bills.

For more details call 0800 028 6122.