5. Property, Plant and Equipment

The major components of property, plant and equipment as at December 30, 2023 and December 31, 2022 were as follows:

	December 30, 2023			December 31, 2022
	Cost	Accumulated depreciation	Net book value	Cost	Accumulated depreciation	Net book value
	Cost	Accumulated depreciation	Net book value	Cost	Accumulated depreciation	Net book value
	$	$	$	$	$	$
Land	238	-	238	238	-	238
Buildings	102,211	21,641	80,570	104,835	16,721	88,114
Machinery and equipment	323,653	95,254	228,399	271,877	78,029	193,848
Enterprise software	16,847	8,156	8,691	22,717	14,750	7,967
Office furniture and equipment	3,568	1,715	1,853	3,719	1,767	1,952
Vehicles	405	258	147	492	305	187
	446,922	127,024	319,898	403,878	111,572	292,306

Interest expense capitalized as part of the construction cost of property, plant and equipment was $0.3 million and $1.2 million for the years ended December 30, 2023 and December 31, 2022, respectively, and immaterial for the year ended January 1, 2022.

As at December 30, 2023, property, plant and equipment included construction in process assets of $33.3 million (December 31, 2022 - $128.4 million) and $11.1 million (December 31, 2022 - $8.8 million) of spare parts inventory.

Total depreciation expense included in cost of goods sold and selling, general and administrative expenses on the consolidated statements of operations related to property, plant and equipment for the year ended December 30, 2023 was $29.3 million (December 31, 2022 - $21.3 million; January 1, 2022 - $17.3 million).