Building energy performance has moved from a cost question to a leasing one. Large tenants, particularly government and corporate occupiers, increasingly specify a rating, which makes performance a valuation issue for owners.
NABERSNZ measures operation, not design
The distinction is the point. Green Star rates a building’s design and construction. NABERSNZ rates measured energy use over a twelve-month period, normalised for factors including hours of occupancy, floor area and climate.
That means a building designed to a high standard and operated badly rates poorly, and an older building operated well can rate better than a newer one. Owners are frequently surprised by their first rating.
Two rating types exist: a base building rating covering services under the owner’s control, and a whole building rating covering all energy use including tenant equipment.
Why it matters commercially
- Leasing. Government agencies and large corporate tenants increasingly require a minimum rating, and a building that cannot meet it is excluded from a segment of the market.
- Rent and value. Better-performing buildings attract stronger tenants on longer terms, which is what drives value.
- Operating cost. Energy is a substantial outgoing, and in a net lease structure it affects the tenant’s total occupancy cost and therefore what they will pay in rent.
- Finance. Lenders offering sustainability-linked facilities reference building ratings.
What actually drives building energy use
In New Zealand commercial buildings the largest loads are typically heating, ventilation and air conditioning, followed by lighting, then equipment.
The measures with the best return are usually operational rather than capital:
- Control settings and schedules. Plant running outside occupied hours is the single most common finding. Buildings frequently condition empty floors overnight and at weekends because nobody reviewed the time schedules after a tenancy change.
- Setpoints and deadbands. Heating and cooling fighting each other, or setpoints tighter than necessary, waste substantial energy.
- Maintenance. Dirty filters, failed sensors, stuck dampers and refrigerant loss all degrade efficiency invisibly.
- Lighting controls — occupancy sensing and daylight dimming, which pay back quickly.
- Metering. You cannot manage what you do not measure, and sub-metering by floor or by system is what reveals where energy actually goes.
Tuning an existing building typically produces meaningful savings for modest cost, and should be done before considering plant replacement.
Capital measures
Where operational tuning has been done, capital options include LED lighting replacement, HVAC plant upgrade including heat pump systems, building management system upgrade, glazing improvement, and solar generation.
Model these on actual measured energy use rather than nameplate assumptions, and include the disruption cost of works in an occupied building.
The split incentive problem
The structural obstacle in commercial property: the owner pays for capital improvements, and the tenant receives the energy saving through lower outgoings.
That misalignment is why energy efficiency investment lags. Mechanisms that address it include green lease clauses sharing costs and benefits, agreeing to a rent adjustment reflecting improvement, and simply recognising that a better-performing building attracts better tenants.
Green lease provisions can also cover data sharing, which owners need for a whole building rating and cannot obtain without tenant cooperation.
The regulatory floor
The Building Code sets energy efficiency requirements, strengthened progressively, and these apply to new building and to some alteration work. Compliance is the floor rather than a performance achievement.
Building warrant of fitness obligations for specified systems also require ongoing inspection and maintenance, which overlaps with efficiency — well-maintained plant is more efficient plant.
Where the seismic question intersects
For older buildings, energy upgrade and seismic strengthening decisions interact. Doing both at once while a building is vacant is substantially cheaper than doing them separately.
Where a building requires strengthening, that is the moment to assess whether services upgrade should be bundled, since the disruption cost is already being incurred.
Where to look
NABERSNZ is administered by the New Zealand Green Building Council, which publishes rating information. EECA publishes energy efficiency guidance and runs programmes supporting building energy projects, with criteria that change — check current programmes directly. MBIE publishes Building Code requirements at building.govt.nz.
General information only, not property or financial advice.
